The cheapest quote isn't the cheapest supplier: total cost of ownership

1. Before you start

Total cost of ownership (TCO) is what a purchase actually costs you across its whole life — not just the number on the quote. Buy a part for $100 that jams the line twice a year, arrives by slow freight, and needs special disposal, and the true cost per usable part might be $150. TCO is that $150; the unit price is only the $100. When two suppliers quote different unit prices, the cheaper quote is not always the cheaper supplier — freight, defects, payment terms, and end-of-life costs can flip the ranking.

Three honest statements before you start:

This is a Decide course. You read a situation, learn the idea, and make a call. You do not write or run any code.
The company in the case, Kestrel Compressors, and its two suppliers are composite — invented from ordinary, realistic figures so the arithmetic is clean. No number is a claim about any real company.
This is not a certification. It shows, to you, that you can defend a supplier call on total cost rather than sticker price.

You need only arithmetic. The hard part is knowing which costs belong in the comparison.

2. The Situation

Kestrel Compressors builds industrial air compressors and buys a machined valve plate for every unit. Two suppliers quote the same part: Anvil Components at $100 and Borel Precision at $115 — and purchasing wants to sign Anvil to “save $15 a plate.” The plant manager is uneasy: Anvil’s plates come by slow ocean freight and fail on the line far more often, and nobody has put a number on what that costs. You have to make the call, and the $15 gap is the least of it.

3. What you’ll be able to do

After this course you will be able to:

Build a total cost of ownership figure for a purchased part — unit price plus freight, quality, financing, and end-of-life — instead of comparing sticker prices.
Decide which supplier is actually cheaper when the lower quote hides higher defect, freight, or disposal costs, and name the number that flips the ranking.
Turn a defect rate and a downtime cost into a per-unit quality cost you can compare against a unit-price saving.
Say when a lower unit price is a false economy, and set the defect rate at which it stops being one.

4. Prerequisites & time box

Prerequisites: arithmetic and percentages. Helpful but not required: the idea that a defect caught late costs more than the part itself (covered in section 6). No spreadsheet, no procurement background. If you have not met the idea of a per-unit contribution, you do not need it here — this course explains every figure it uses from the ground up.

Time box: about 21 minutes of reading (measured), plus your own thinking time on the call. That is under the 25-minute cap for a concept course.

Difficulty: 4 / 8 — a new-manager decision: a couple of interacting factors and one real judgment call, where the obvious answer is often the trap.

5. The case & where the numbers come from

Kestrel Compressors is a composite business-to-business industrial manufacturer: its part cost, defect rates, freight, and terms are built from ordinary figures a mid-sized equipment maker would recognise, chosen for clean arithmetic and not drawn from or claimed about any real firm. Anvil Components and Borel Precision are likewise invented suppliers. The definitions — total cost of ownership, landed cost, cost of poor quality, payment terms, end-of-life cost — are standard and cited in section 11. Every figure below is an in-course assumption; every later number is computed from these.

Item	Anvil Components	Borel Precision
Unit price per valve plate	$100	$115
Inbound freight & duty per unit	$9	$3
Defect rate (fails on the assembly line)	5%	0.5%
Payment terms	net-30	net-60
End-of-life disposal per unit	$6	$4

Two figures are shared across both suppliers, because they describe Kestrel’s own plant, not the part:

Shared assumption	Figure
Annual volume of valve plates	12,000 units
Cost of one defect caught on the line (scrapped part + teardown + ~30-min line stop)	$700
Kestrel’s annual cost of capital (for the financing calc)	12%, 360-day year

6. The Concepts

Unit price versus total cost of ownership

The unit price is the number on the quote: Anvil $100, Borel $115. On that number alone, Anvil wins by $15 a plate, and over 12,000 plates that looks like $180,000 a year of savings. Total cost of ownership asks a different question: across the whole life of each plate, from the moment you order it to the moment you dispose of it, what does one usable plate really cost you? That figure adds four things the quote leaves out — the freight to get it here, the cost of the ones that fail, the financing effect of when you pay, and the cost to retire it. Each of the next four concepts is one of those additions. Only when all four are in can you compare the two suppliers.

Landed cost: unit price plus freight

Landed cost is the unit price plus everything it costs to get the part to your dock — freight, duty, insurance. Anvil’s plates come by ocean freight from far away: $9 a unit. Borel is domestic: $3 a unit. So the landed cost is Anvil $100 + $9 = $109 and Borel $115 + $3 = $118. Freight has already eaten $6 of Anvil’s $15 unit-price advantage: on landed cost, Anvil leads by only $9, not $15. Freight is the easiest hidden cost to forget because it arrives on a separate invoice from a different vendor, but it is caused by the sourcing choice just the same.

The cost of poor quality

A plate that fails on the assembly line does not just waste the plate — it stops the line. Kestrel measures one defect at about $700 all-in: the scrapped plate, the teardown to pull it, and the roughly 30-minute line stop while a good plate is fitted. That $700 is the same whichever supplier sent the bad plate. What differs is how often it happens. This is the cost of poor quality, and per plate purchased it is the defect rate times the cost of a defect:

Anvil at 5%: 0.05 × $700 = $35 a plate.
Borel at 0.5%: 0.005 × $700 = $3.50 a plate.

That single line is a $31.50-a-plate swing — more than twice Anvil’s whole $15 unit-price advantage. The cheap plate is cheap because it fails, and the failure lands on your line, not the supplier’s. This is usually the largest hidden cost in an industrial part, and the one purchasing is least likely to have on the quote.

Payment terms as a financing cost

Payment terms decide when you pay, and money you keep longer is money you can use. Anvil is net-30; Borel is net-60. Holding the cash an extra 30 days is worth roughly the unit price times your cost of capital times the days, over a 360-day year:

Anvil (net-30): $100 × 12% × 30 ÷ 360 = $1.00 a plate of financing benefit.
Borel (net-60): $115 × 12% × 60 ÷ 360 = $2.30 a plate of financing benefit.

Terms reduce the cost of ownership — they are a benefit, so we subtract them. Borel’s longer terms are worth $1.30 a plate more than Anvil’s. Notice how small this lever is next to quality: $1.30 versus $31.50. Terms are real and belong in the model, but they rarely decide an industrial sourcing call on their own. Knowing that keeps you from over-weighting the number a procurement negotiator is proudest of.

End-of-life cost

The last cost lands when the part is retired: end-of-life cost — disposal, decommissioning, recycling, or hazardous handling. Anvil’s plate carries a coating that needs special disposal: $6 a unit. Borel’s cleaner plate is $4 a unit. It is a small line, but it is a real cash outflow the quote never shows, and it runs the “wrong” way here — the cheaper-quote supplier is also dearer to dispose of.

Putting it together: the TCO comparison

Now add the five components for each supplier — landed cost, plus quality, plus end-of-life, minus the financing benefit:

Component	Anvil	Borel
Landed cost (price + freight)	$109.00	$118.00
Cost of poor quality	$35.00	$3.50
End-of-life disposal	$6.00	$4.00
Less: financing benefit of terms	−$1.00	−$2.30
Total cost of ownership per plate	$149.00	$123.20

Borel’s TCO is $123.20; Anvil’s is $149.00. The supplier with the higher unit price is $25.80 a plate cheaper to own — and over 12,000 plates that is $309,600 a year. The $15 “saving” on Anvil’s quote was not a saving at all; the defects and freight it hid cost far more. Sign Borel, and put the real comparison — not the two quotes — in front of purchasing.

The number that flips the call is Anvil’s defect rate. Hold everything else and lower Anvil’s defects: at 0.5% its quality cost falls to $3.50 and its TCO drops to $117.50 — now below Borel, and Anvil wins by $5.70. The break-even is about 1.3%: if Anvil could get its defect rate under roughly 1.3%, its lower unit price would finally make it the cheaper supplier. Freight alone will not do it — even at Borel’s $3 freight, a 5% defect rate leaves Anvil at $143, still dearer. Quality is the lever; the quote is not.

(An interactive calculator sits here — enter each supplier’s price, freight, defect rate, terms, and disposal cost, and it returns both TCO figures, the annual gap, and which supplier to choose. Drop Anvil’s defect rate and watch the decision flip.)

7. Your Call

You have seen how landed cost, quality, terms, and end-of-life build Kestrel’s TCO and flip the supplier ranking. Now a different call lands on your desk.

Talon Rail Systems — a composite maker of railcar braking assemblies, a different company in a different corner of the industrial world — buys a friction brake pad for every assembly, 8,000 pads a year. Its incumbent supplier is Cardinal Friction; a challenger, Delta Brake, has quoted a lower unit price to win the business. Because a brake pad is safety-critical, a line defect costs more here — Talon puts it at $900 a pad (scrapped pad, teardown, and a longer line stop). Talon’s cost of capital is again 12% on a 360-day year. The figures:

Item	Cardinal (incumbent)	Delta (challenger)
Unit price	$60	$52
Freight per unit	$4	$7
Defect rate	1%	4%
Payment terms	net-45	net-30
End-of-life disposal	$2	$5

Here is the wrinkle that was not in the Kestrel case: switching to Delta is not free. Because the pad is safety-critical, qualifying a new supplier means a one-time requalification and retooling cost of $120,000. So your call is not just “which supplier is cheaper” — it is whether to switch at all, given that switching itself costs money up front.

How this differs from the taught case (the transfer): this is a different company and subject (Talon’s safety-critical rail brakes, not Kestrel’s compressor valve plates); the numbers are different so the TCO arithmetic must be redone from scratch; the decision type is different — a switch / stay call about an incumbent, not a clean pick between two fresh quotes; and there is an added constraint — a one-time $120,000 switching cost with no counterpart in section 6. The core concept is the same: total cost of ownership, not unit price, decides the supplier call.

8. Self-check

Before you write the memo, make sure you can say each of these in one line:

Why is “Delta’s quote is $8 lower, so switch” the wrong test for a supplier call?
Which single hidden cost does the most to flip the ranking here, and why?
What defect rate would Delta need to hit before its lower unit price actually made it cheaper to own?

If any is fuzzy, reread section 6 — landed cost, cost of poor quality, financing, and end-of-life are the whole comparison.

9. Stretch

Push the decision further on your own:

Back at Kestrel: at what freight cost would Anvil’s plate reach the same TCO as Borel’s, if its 5% defect rate were fixed? (The genuinely harder one: hold defects at 5% and solve for the freight that makes Anvil’s TCO equal $123.20 — then check whether any real freight quote could get there.)
At Talon, suppose Delta will fund a quality program that cuts its defect rate to 1.5% but adds $3 a pad to its price. Redo Delta’s TCO. Does switching now pay back the $120,000 requalification cost within a year?
Write the one sentence you would say to a buyer whose bonus is tied to unit-price savings and who keeps pushing the lowest quote.

10. Ship it — your decision memo

Write a one-page memo to Talon’s head of procurement. State the call (do not switch to Delta; stay with Cardinal, whose TCO is $74.10 a pad against Delta’s $99.48). Show the five-line build for each supplier, and highlight the one line that decides it — the cost of poor quality, $9 against $36 a pad. Name what you rejected (the $64,000 unit-price “saving,” and the idea that a lower quote is a lower cost) and why. Name the one thing that would change your mind (Delta getting its defect rate near Cardinal’s — below roughly 1.5% — at no extra price). Fold in the $120,000 switching cost as the final nail: even if the two were close on TCO, the up-front cost would have to pay back, and here there is nothing to pay it back with. Keep it to a single page a procurement head grasps in two minutes. This memo is your own argued claim — not a credential.

11. Sources

Kestrel Compressors, Talon Rail Systems, and their suppliers, and every dollar figure attached to them, are composite — constructed from ordinary, realistic figures for clean teaching arithmetic, not drawn from or claimed about any real company. The concept definitions used to reason about them are standard; references below.

Concept / claim	Source (publisher)	URL	Accessed
Total cost of ownership across a purchase’s life	Wikipedia — Total cost of ownership	https://en.wikipedia.org/wiki/Total_cost_of_ownership	2026-07-19
Landed cost = unit price + freight + duty	Wikipedia — Landed cost	https://en.wikipedia.org/wiki/Landed_cost	2026-07-19
Cost of poor quality (defects, scrap, rework)	Wikipedia — Cost of poor quality	https://en.wikipedia.org/wiki/Cost_of_poor_quality	2026-07-19
Net-D trade payment terms (net-30, net-60)	Wikipedia — Net D	https://en.wikipedia.org/wiki/Net_D	2026-07-19
Cost of capital used to value payment terms	Wikipedia — Cost of capital	https://en.wikipedia.org/wiki/Cost_of_capital	2026-07-19
End-of-life disposal / decommissioning cost	Wikipedia — End-of-life product	https://en.wikipedia.org/wiki/End-of-life_product	2026-07-19

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