I saw this yesterday when doing some scouting around on eBay for my first project and was struck by this entry as well. Personally, I love the old Atari Gauntlet cabs but knew this wasn't an original MK. Still, aren't there a couple marquee places that will do custom work? I could definitely see MK art in the Gauntlet styled Grill Marquee and redoing the CPO with the 2nd player stick and buttons pushed a little more to the right to make it a little more even. Is the marquee/grill removable as well, because painting the MK logo over the speaker grill might make that look very cool.
As for guessing the reserve... I'd say $600 is a bit lofty, even for someone that isn't in the know. $400 seems a bit more likely.