I imagine that just like used cars there are plenty of dreamers who advertise very high prices, refuse to negotiate, and then find themselves 6 months later still in possession of the item they wanted to sell quickly.
Just like everything there are dreamers on both sides of the fence, sellers and buyers.
Plenty of people buy items purely on price, without any understanding of why one item costs more than another.
Like Nino said if the dealers spent as much time as a hobbyist does on a restore they would go broke, they play the numbers game if they can sell "x" number of machines and only a percentage come back for repairs then they still make profit, win on some lose on some but overall come out in front.
If someone wont negotiate and end up not selling then perhaps they REALLY didn't want to sell it.
