Well, the process of rebuilding the carburetor is really simple. you just have to take your time and make sure all the new parts go back in, the same way that the old ones came out. And, you should be able to pick up a decent rebuild kit for around $30 or less. However, the time consuming part is getting everything tuned just right once you get the carb back together.
take a look at this thread, http://www.ifsja.org/forums/vb/showthread.php?t=101921
it's prety much a step-by-step for rebuilding a 2150 (that's the carb that should be on a 90 GW).