Cost is a consideration in many of the things we purchase. How much something costs affects whether we can afford it or once we've bought it, can we afford something else. Not only how much is the thing "priced" at, but also is it worth that amount? Could you get it or a substitute at a significantly lower amount? So, we consider how much it costs when we buy a home and when we buy many of the contents (furniture, appliances, and furnishing).
Costs can be expressed in different ways. There is the total cost --the initial cost plus any on-going or necessary supplementary costs. For some purchases, the unit price (or cost) provides a useful way to compare different volume prices.