Fliskits has Micro Maxx motors, a complete line of micro parts and over a dozen real built-it Micro Maxx kits.
The original manufacturer of the Micro Maxx line is Quest Aerospace. They were sold to Aerotech several years ago but are another good source for Motors and a few building parts. They may also still have some of the first run Micro Maxx RTF models we maxxers refer to as LPB's (Little Plastic Bricks)
A.S.P. has several very nice Scale model Micro Maxx Kits. Don't know if Andy still sells MMX-II motors.
If you ask your local Hobby shop to order a case(12-6pks) of MMX-II motor or more they can usually get them within a week or so.