Well if you already had a V2 in it and working that answers my question. To answer yours, I highly doubt you'll find a gearbox in the price range you're looking at. I just checked the classified here and complete gearboxes start at $80, going up to $400, and these are the used ones. Perhaps there's someone on the BCAC forums that can help you better.
Sorry to say, if you don't have the time to meet with an age verifier, there's not much help we can give outside of what we have.
ASC & RAAT Age Verifier for Central Alberta
Authorized G&G Dealer.