I just bought a dedicated Skins Game from Namco about 2 weeks ago for $495! The thing is immaculate. It was located in amovie theater and hardly ever played. Even the game manual was still in the cabinet!
The condition of each game varies by a lot, but they all list for the same price. So you'll be doing yourself a favor by personally checking out each game that you're interested in. The thing about Namco is that if a phone number isn't listed, then the machine is at a site like a pizza joint, or movie theater. The ones with the phone numbers are usually a Namco Arcade.
If you see a game that you want to buy, forget emailing them. I've never gotten them to answer. However, you can call Kurt (Kirk?) at 630-238-2200 x2317 and ask him about the games. He's in charge of used game sales. He'll tell you where the game is located and if you're interested, he'll get you the contact info of the route manager. The route mgr is the person that you'll meet up with to pay and pickup the machine.
Hope this helps.
Impostor