After weeks of searching I finally found this at a Gamestop last Monday, they got 1 copy and it was the first one they ever had. A bargain for $20, I would have been dissapointed if I paid more that $30 though. Very fun, definitely worth the search and it's positive metacritic score.
Much more suited to the Wii than the PSP, the Wii-mote makes it, whoever did the motion control development should do the next Monkey Ball game.
Wii Code 3456 7941 4060 2924