Forgot that the question was really about worth. 1. In a truly free market, nothing is necessarily worth what is being asked, not even when the thing sold is in high demand. 2. It's worth only the max that someone is willing to pay for it. That figure is agreed to by the parties in each particular case and so is not set in stone but will fluctuate. 3. A general price range can be determined (guessed at) but that too will vary over time. All this seems obvious but often it isn't.