Howdy Dan,
The last 2 or 3 i'd been watching on ebay went up around $800, i think all 3 started at $500, but these were all working machines, so i think $500 for the "GI only" one you're looking at is fair.
I think there's mixed thoughts on it as many people hate ultra-wide bodies (too slow) and lacking things to do compared to modern dmd machines.....but then the superhero factor kinda compensates too ;-)
At the end of the day, it either grabs you, or it doesn't.
Sadly it's a gen2 cpu board, which is a little more of a bitch than the gen1 (middle earth) board.
I have more gen1 boards as spares, but no gen2 stuff.
MM.