You're best bet for an MR would be ebay or the Junkyard here. Find one that somebody is selling from their collection. I've seen several here recently. Just use the "search" periodically and look for "rocketeer" in the junkyard. Might take a few weeks but you'll probably find one.
As for kits, it depends on what you want. If you want cheap and inaccurate... as always... ebay. If you want accurate, it'll cost you around $200 and you can order one from Monsters in Motion.