Suppose you buy a gallon of gas for $3. How much did it cost you? You say, “Williams, that’s a silly question. It cost $3.” That’s where you’re mistaken, because there’s a difference between price and cost.

To prove that price and cost are not the same, consider the following. Suppose you live and work in New York City and routinely pay $15 for a haircut. Imagine you were told that there’s a barber in Boise, Idaho, who can give you the identical haircut for just $5.