I saw a nice Monster Bash sell a few weeks ago with a brand new playfield installed for $8500 cash.
So $6500 for a nice game is on the money, if its really nice. They have come down a few grand in this over stocked market. Having said that, I would buy 2 better games for the same money if I wasnt after a Monster Bash.  Monster Bash does look the goods in any collection however.

I think $6500 is right. It seems at the moment, every man n his dog is selling a really nice title at a really great price in really great condition.
Seen how many great machines are on Ebay. The dealers are full, the private container sellers are full.  New Sterns are selling. So many dam good choices.
Its the best time to win Lotto and stock up on really cool machines.lol