The value of something is how much someone is willing to pay for it. The consumer drives the market. Try selling your vehicle for what you think it's worth. Whatever you get for it is how much it's worth. Look at eBay. People pay for what they think something is worth. All the people who set reserves on what they are selling usually wait for it to sell until someone thinks it's worth what's being asked for it.
The value of something is what someone is willing to pay for it.