Toggle switch replacement
If your were in the UK - it would almost be cheaper to buy a new transmitter than to buy a replacement switch!
You can easily buy toggle switches - its also reasonably easy to replace them. The only trouble is that the futaba toggles are quite big .. I have never found anybody, except the Futaba importers service shop, who actually stocks the correct sized switch.
You are probably faced with the same problem. Suggest that you ring the nearest repair shop and insist that they sell you the right switch.
On the overhand you might be able to buy a cheap futaba TX and use it as a source of spare parts.