Just got back from the auction after having some games and helping get some of the machines going.  As Max said, there is a wide variety of machines there with quite a few Williams Sytem 11 games that you don't see around too often.  Check out the Bally Playboy to see just how bad an overlay can look...

Worth a visit if you are at a loose end on Sunday, but remember if you want to buy to check the machine carefully and set yourself a maximum price before bidding begins (keeping in mind the 'buyers premium').