STEP 1. Know
your subject! As in any other purchase, an informed decision is a
better decision. I recently got what I thought was a deal on an arcade
cabinet for $75.00, only to have two other people tell me they got the
same thing for $50.00 or less. I *still* think I got a good deal,
but might have been able to haggle it down some had I known the going rate.
SO -- how do you get to know your subject? Check out these resources:
The Rec.Games.Video.Arcade.Marketplace newsgroup is another must visit. Lots of overlap from R.G.V.A.C., but more oriented towards the actual buying and selling of games and parts.
By the way, you might expect that Rec.Games.Video.Arcade would be a good group to read as well - it might have some good info at that, but I have not found it nearly as helpful as the previous two groups.
The Buying From An Operator FAQ - an essential read. Much of the information on this site is a duplicate or rehash of information contained in this FAQ.
The Video Arcade Preservation Society is another great stop. Chock full of nuts like you interested in this hobby. You'll find yours truly listed there.
Another must visit is the Killer List Of Videogames site. It's a database of arcade machines that's constantly in the process of being updated.
You'll notice a lot of my links point to a place called "Spies" -- they host the Wiretap Arcade Games Collector's Archive. This is an excellent resource for arcade game collectors. Pinouts, manuals, switch settings, links, etc.
No list of sites would be complete without RandyFromm.com -- if you visit no other site, you should visit this one. Want to *really* learn what makes arcade games tick? This is the place!
And last, but most
certainly not least - you must visit Videotopia!
Don't ask, just go! :)