Keep in mind that the true momentary value of anything is simply the highest price someone is willing to pay for it.
To illustrate this concept, let me tell you a story about a friend of mine who was trying to sell a house:
Him: I've had my house on the market for a year. I'm asking $90K. This sucks!
Me: Are you advertising?
Him: Yep. No problems in that department. It's in all the listings.
Me: Then it's priced too high.
Him: No it isn't!! In fact, I have it priced $5K below the appraisal value! And other homes in the area are going for about the same amount. I've done my homework, and it's definitely worth every bit of $90K!
Me: No it isn't.
Him: Huh?
Me: The true monetary value of anything is the highest price someone is willing to pay for it. For whatever reason, no one is willing to pay $90K for your house, hence the house is not worth $90K.
Him: Um, O.K. Then how do I find out what it's worth? How do I know what to set the price at?
Me: Simple: Start off with a high asking price. And then, over time, slowly increment the price down. Keep lowering the price until someone buys it. At that point you'll know precisely what the house is worth.
Him: Oh. O.K.