I think TRE might be the only place to buy double syncros. BM and Shep have them i think, but i dont know that they sell them seperately from their trannies.
Conicelli sells evo forks for cheap, but they have plastic wear pads. TRE sells much spendier Evo forks that are moddified with metal wear pads. When I talked to John at TRE he also recomended getting upgraded shift rails when you got heavy duty rails, as that would then be the weak link.
I would poke around on their site a bit and come up with a parts list that fits your budget.
TRE
Threaded Mode