The only objective way to determine the value of something is to observe what people are willing to give up in order to get that thing. And because money is the

The only objective way to determine the value of something is to observe what people are willing to give up in order to get that thing. And because money is the convenient means by which we exchange value, it's how we can observe how much people actually do sacrifice to get something. And price is just the expression of that money value. As mentioned elsewhere, hours of labor is pretty thoroughly discredited. It implies that I could cause something to be worth more just by using inefficient methods. It fails to capture the idea of marginally decreasing utility. Basically, the value of something is in the eye of the beholder, and tying value to production labor just completely fails to see that.