Monitor issues can usually be fixed fairly easily as a previous poster stated, usually with just a cap kit. Sometimes, they don't even need that. I just bought a game a few weeks ago and the guy stated that the monitor is scrambled but you can kind of see a picture. I realized even before I went to look at the game that it was JAMMA and it would be a neg sync monitor hookup. When I was inspecting the game, I saw that someone had tried to solder a jumper over the neg sync connections but had the JAMMA video hooked up to the pos sync. I said, no problem, I'll take the game off your hands for $100. Got it home, clipped off the solder, made a new connector for the neg sync, guess what - I got a picture! A little fine tuning of the colors and a cap kit, CRT works just fine!
Bottom line on the GORF, if you don't mind doing CRT repair (or learning how to) then $200 would be a good price if all else is in good shape on the cab. If you identify the monitor and read the CRT forums, you should be able to get a rough idea of what is causing the problem and how to fix it.
Best of luck!
-Muel