robotron is my new fav game so i would get that.
on a side note, do you only have to register if you are selling something at those auctions?  id like to go to that one just to see what it's like.
I wrote this up a while back with the help from Mario D's orriginal writeup. This should give you a somewhat cloudy idea of what it is like. You should go. They are great fun. 
http://wiki.arcadecontrols.com/wiki/Arcade_Auctions_1I am going to the august 12 DFW superauction...I want all  those  games above, but I can't get all of them...well...we would have room...but not enough money  ...please post which ones you would buy, and how much you would  pay...
...please post which ones you would buy, and how much you would  pay...
Man o man, the Qbert, Robotron, and Donkey Kongs if they are in any reasonable condition will run you at a minimum $300+. Robotron probably even more. Mappy... for such a stupid game, I still really love it!!! It is one of the first MAMEd games I played. I saw a Crystal Castles go for pretty cheap at the last Auction. It looked like it had some monitor issues, but I talked to the guy who bought it (he came to my house when he bought my SEGA ThunderBlade). He said that it was a vhold issue and it plays fairly well. NG 4 Slot...TravistyOJ got one of these several auctions ago. I think he paid about 375 for it. They auctioned it as a 2 slot and when he opened it, it was a 4. (I think that was the numbering) anyway he made out well. Bezerk... I don't think I have ever seen one at auction. cant speak at all for the others. 
Bottom line, what is it worth to you. My first auction I went with Defender as #1 on my list. I got it for $375. I felt good about it. I played the heck out of it. When the play slacked off, I sold it on ebay for $450 which just about payed for the auction cost and the buyers premium and the new video decoders I had to buy for it. If you figure $.25 per game, I probably paid for about 20 games, the rest were all free, plus the grins for actually having one in my house for a few months.