Objetivist theory of value
There has to be some merit to objectivism, or inventors could never invent anything. If value truly was up to the whims of the buyer, you could never know in advance what is going to be considered valuable. But because value is not just a result of the subjective needs of the buyer, the inventor can predict in advance tha what he has thought of has value. Value is just as much a result of man's use of reason to solve his needs, as it is a result of the needs of the buyer.