don't overpay for worn, dirty stuff. This is one of the main problems that artificially skewed the market in the first place. When things don't work, you have to add more money off for the unknown. Because you really don't know how complex and frustrating it's going to get. So you price for worst case scenario. $4500 seems spot on. Dirty as shit, probably cracked ramps here and there, warped plastics, scratched and dinged cabinet with mechanical/electrical problems. Pops not working. Could be a switch, could be a transistor, could be the back of the board is hacked to shit and looks like a roadmap of traces. Something like that, you price it as if you had to replace the board. That is worst case. That is the proper way to figure out routed, dirty games.