You're best bet is either going to be Ebay or Yahoo Japan.
The show has been over for a few years, so finding one is going to take some hunting around.
I've seen plenty on Ebay for sale. Try Rangerboard also.
Heres a Bootleg though, same person I got my bootleg Gourai Changer (which is better than BA's Thunder Morpher, 3 times better than the Thunder Morpher)