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.
Cost, in common usage, the monetary value of goods and services that producers and consumers purchase. In a basic economic sense, cost is the measure of the alternative opportunities foregone in the choice of one good or activity over others. This fundamental cost is usually referred to as opportunity cost.