It's an interesting topic. I think it really just comes down to the cash flow of the dealer. If they can afford to wait 12months to sell a game for $5000 when its really only worth $3000 then they can choose to do that and good on them I suppose. If however they can't afford to keep that sort of money locked up in stock, they will have to reduce the price.

Logic also gets in the way of a good story so it is often overlooked by the seller. Eg, I'm sure we all have a friend who has bragged about buying a product (any product) for $X and then sold it for twice as much at some point in the future. They usually gloss over the fact that 10 years has passed, that they had to spend half the purchase price again on maintaining and storing the product, etc. They then try to impress people by saying "I doubled my money" but it would be untrue and they probably could have made a better return elsewhere.

Regarding ads on eBay for $15000 KISS machines: Even though a seller has the right to set the price as high as they want, I can't help but make a mental list of sellers that I would never purchase from based on these ads. Even if they were selling something I wanted for a reasonable price I'd feel like I'd rather give my money to someone else who isn't gouging the market.