I have a friend who bought one from a storage unit seller about a month ago. I think he paid $250 for it and it had probably been in that unit for the past 15 years, at least. Needless to say I was ultra jealous.
But as you probably already are, I'd stalk Craigslist since that is where my friend found this guy. Also check for arcade auctions since these are relatively common at them. I'd recommend these guys; I went to one of their auctions a few years ago and they had machines going out the door for as low as $25.
http://www.americanamusementauctions.com/calendar.htmThere's also a company called Super Auctions that I've utilized before, but they've been dormant for about a year now. not sure if they went out of business or what.