Got a Sega Saturn and $70.00 to blow? The you might want to check the all too uncommon "special edition" of Rockman X4. This little gem is currently up for grabs on ebay, complete with the exclusive Ultimate Armor model kit.
Collectors should also be on the lookout for the PlayStation variant of the pack which is even rarer: same package, different system but released in a smaller amount than the SS version. I've yet to see it anywhere beside Yahoo! Auctions Japan, but you never know.