If that's the DX belt, then the Mission Memory can be removed for use in the rest of the Faiz Gear as shown
here.
As for where to find it, Ebay or something similar, maybe HLJ, if your lucky. Good luck.
EDIT: Just had a look at HLJ. they're listing it as out of stock. Whether or not that means they CAN get one in I don't know. You could place an order and see, but i don't like you're chances. Best to keep an eye on Ebay and the like.