Actually the price of a good is almost always the cost to manufacture and sell. If it were not, someone else would manufacture and sell it at cost. Bear in mind that the profit inherent in captialism corresponds to the cost of the capital required to run the manufacturing and sales process.
Of course, goods fall on a commodity range. Some things are entirely fungible, others less so. The less fungible a good is, the more the cost can move away from the cost to produce.
Books sound like they aren't fungible - after all one title isn't an exact replacement for another. But, they are quite fungible in the sense that one murder mystery can in some sense substitute for another.
Can you though?