Beating this topic to death.

Study the graph at the top of the page. Prices are going to go up, as the number of machines sold declines. It will head that direction for a long long time as far as machines that are no longer produced.
http://www.bostonpinball.biz/ebay0512.htm

BS. People who got in this hobby earlier, as pinball was on the decline have made a killing. I keep hearing about people who bought for x and sold recently for x+. It's very difficult to do that right now. I keep hearing about folks who traded up, too. I have yet to trade up. I consider it extremely fortunate if I can break even. Rising prices are frustrating to the recent newbies to this hobby. People are asking ridiculous money, because they can (and some folks actually get it). At least when I go to sell I keep it reasonable, and still have trouble selling. A lot of folks out here fighting at the bottom to find affordable pins, but the folks with big bankrolls shelling out big cash for A list games are driving all the B and C list games sky high. That is exactly what is happening.