If you are looking for a cab to Mame, then you probably won't have to worry about Mr. Do! very much. He mostly seems to deal in mainline classic games, mame cabinets (already made), and brand new stuff.
I was only a few feet away from him almost the entire time at one auction (he stuck with the auctioneer, who was totally in on it). Everything he bid on at that auction was classic, new, or MAME.