If you're after single taper needles, you could also call Sudco or CPW. Multi-tapers like the NEDW etc that you see discussed in threads are proprietary to a specific OEM and you generally have to see that brand's dealer, although I called 10 Suzuki shops before hitting on a source for a needle I was after.
The RB carb mod is a nice way to spend your money, but is by no means necessary. The stock carb can be made to work fine with needles and jets.