valley. (building construction). An inside angle formed where two sloping sides intersect. (geography). A generally broad area of flat, low-lying land bordered by higher ground.
In ordinary usage, price is the quantity of payment or compensation given by one party to another in return for goods or services.
Economic cost is the combination of gains and losses of any goods that have a value attached to them by any one individual. Economic cost is used mainly by economists as means to compare the prudence of one course of action with that of another.