1, 4. Price, charge, cost, expense refer to outlay or expenditure required in buying or maintaining something. Price is used mainly of single, concrete objects offered for sale; charge, of services: What is the price of that coat? There is a small charge for mailing packages. Cost is mainly a purely objective term, often used in financial calculations: The cost of building a new annex was estimated at $10,000. Expense suggests cost plus incidental expenditure: The expense of the journey was more than the contemplated cost. Only charge is not used figuratively. Price, cost, and sometimes expense may be used to refer to the expenditure of mental energy, what one “pays” in anxiety, suffering, etc.

Did you mean unit price?