There is a well-worn idea, usually attributed to a fictional police officer in a Terry Pratchett novel, that being poor is expensive: the man who can afford good boots buys one pair that lasts ten years, while the man who cannot spends the same money on ten pairs of bad ones and still has wet feet. It is a good story, and like most good stories it is only sometimes true.

The useful question is not whether expensive things last longer. It is how to tell, before you hand over any money, which category the thing in front of you belongs to.

Price is what you pay once. Cost is what you keep paying

The clearest cases are the ones where the purchase price is not the real price at all.

A cheap inkjet printer is the standard example, and it earned that status honestly: the hardware is sold at or below cost because the cartridges are where the money is made. Two years of ink can cost several times what the printer did. The advertised number was never the number.

The same shape appears in less obvious places. An appliance that is inexpensive but has no available spare parts is not cheap — it is disposable, and its cost includes the replacement you will buy when a ten-pound component fails. A “free delivery over £40” threshold that reliably makes you add a fifteen-pound item you did not want is not free delivery. A subscription that is cheap monthly and awkward to cancel is priced on the assumption that you will forget.

None of this means the cheap option is wrong. It means the sticker price is answering a different question from the one you are asking.

Cost per use is the number that matters

The single most useful habit here is to stop comparing prices and start comparing cost per use.

Divide what a thing costs by the number of times you will realistically use it. Not the number of times you imagine using it in your most optimistic mood — the number you would bet money on.

A £200 coat worn four times a week for five winters costs roughly twenty pence a wearing. A £40 coat worn the same amount but replaced every year costs about the same, plus four shopping trips. A £200 piece of exercise equipment used enthusiastically for six weeks and then never again costs about £5 each time and takes up a corner of the room for years.

The arithmetic is trivial. What makes it powerful is that it forces the honest question — how much will I actually use this? — into a decision that usually avoids it.

Where the rule breaks down

Cost per use assumes you know the usage. When you genuinely do not, the cheap option is often the correct one, precisely because it limits what you lose if the answer turns out to be “twice”.

Buying the inexpensive version first, and upgrading only once you have proven to yourself that you use the thing, is not a failure of planning. It is how you find out what you actually need without paying for the privilege.

When cheap is simply the right answer

There are whole categories where buying the expensive version is money set on fire.

For anything that draws power, the running cost is the part the price tag hides completely. Efficiency labelling exists to make that comparable — the US ENERGY STAR programme publishes figures by appliance category — and across a ten-year life the gap between two similarly priced machines can exceed what either of them cost to buy.

Things that will be obsolete before they wear out. Technology that is replaced on a two- or three-year cycle rarely justifies paying for a build quality that would last ten.

Things you will use rarely. A tool needed once a year is a tool to borrow, hire, or buy cheaply. Cost per use punishes expensive purchases with low usage more harshly than anything else.

Things where the premium buys a brand rather than a difference. In some categories the expensive option genuinely is better made. In others you are paying for the label. The honest way to tell them apart is to look for a specific, checkable difference — the material, the warranty, the availability of parts — rather than the general impression that it feels nicer.

Things you are buying to become a different person. The equipment for the hobby you intend to take up has a famously poor record. Buy the cheap version, discover whether you are that person, and upgrade if you turn out to be.

A short checklist before you buy

  • What will this cost me over a year, including consumables, repairs and subscriptions?
  • How many times will I actually use it? Divide.
  • Can it be repaired, and are the parts available and affordable?
  • If I am wrong about how much I will use this, which mistake is cheaper to have made?

Four questions, none of which take more than a minute. They will not make every purchase correct, but they will catch the ones where the low price was doing the work of an argument.

When a purchase does go wrong, knowing what you are entitled to matters as much as the arithmetic did; the US Federal Trade Commission’s consumer advice pages are a readable starting point.

More of this kind of thing is in our Home & Living section, including where the heat actually escapes from your home.