Big stuff often goes REAL CHEAP. For several reasons. First off no one wants to lift the stuff. Secondly, it is often hard enough to convince the wife/parents to let you bring home a 19" cabinet, much less a 27" one, or a Dual Cybersled or Full Motion Afterburner cockpit. BTW, oddly enough, spouses/parents will usually agree to a cocktail easier than anything else, despite the fact that one cocktail eats up as much square footage as 3 uprights (because of the chairs you need).
Next thing, is dead games go for really cheap, unless they are A list classics, or nearly brand new. Middle of the road dead games go for nearly nothing because no one wants to mess with them (and more than half the people at the auction have no idea that normal people can repair games anyway)
Lets say my truck can hold two games, sure I might waste one of those spaces on a non-working Galaxian, but I sure am not gonna be dragging home a dead Crime City unless there was nothing else at the entire auction to be had.
Finally, most dead games usually only have one major problem, because once one thing goes, the game goes out of service, preventing other things from happening. BUT, unscrupulous sellers will sometimes swap in a bad monitor into a game with a bad boardset, maybe even a bad power supply too. Leaving a potential buyer with a game that NOTHING works on.