Rent A Hero never got released, and EB Games canceled my preorder for that game long, long ago. Funnily enough, there's a used game listing for it on Gamestop.com, though it will forever be "Back Ordered." I guess the only rare version of the US Rent A Hero will be the review copies given to the game magazines over a year ago.
Shin Megami Tensei IX rare? Maybe, I dunno, but it can be found here on the cheap (for an import):
http://www.play-asia.com/paOS-13-71-4q-77-3-15-shin+megami+tensei-70-1uq.html
I would agree with Kakuto Chojin, not necessarily because it is extremely rare, but because it's the game that "doesn't exist." After Microsoft "recalled" it (actually, at least Gamestop stores, we were ordered to destroy them, which usually means "give to the employees"), the listings for the game (including the guide!) were removed from the system. Try searching for it at ebgames.com. No listing there. Try looking for it on Microsoft's Xbox website. Not listed there either.
I have a copy, and although the game is blah, it's fun to own a game that "doesn't exist." And where else can you own a fighting game with Batman, Jet Set Radio, Britney Spears, and "Fight Club" Brad Pitt look-alikes?