I got my machine there (the one I'm maming).. and I must tell you, the auction is not for regular people like you and I..
If you go multiple times (like I have) you'll very quickly realize who the regulars are, and notice how many machines they always purchase..
you are bidding against arcade operators.. they're budgets will always be higher than yours.
I ended getting my machine (X-men children of the Atom, with 27" display) for only 150$CDN.. and that's a really good price!!
My suggestion.. be there early.. pick up a list.. choose 5-10 machines you really want.. and write down the price next to it that you're willing to pay for it..
then when the bidding begins, bid to that amount.. I've got my machine on my 3rd pick and was happy with it.
Forget pinball.. forget table tops.. according to most operators.. these (and the golf game) are the only machines that make $$$ for them now!
Also.. bid early.. with 2 identical machines, the first one always sells for less! The reason being, of the 100+ machines at the auction, people want to scope prices out first, and bid less for machines at the beginning.. while at the end, some bug bites them, and they want a machine at any cost!
Good luck!