Hi there Hydrogen, welcome to the forums. Its good to see someone else here from SA. Where in SA you from?
There aren't too many plaves here where you can get go kart parts, but i have found 2. The first one
Grogro Industries sells centrifugal clutches and torque converters for go karts. The second one,
Checkmate Products sells all things to do with go karts. They also manufacture them.
Unfortunately everything here is crazy expensive, cos it is all imported from America. If you have some way to buy direct from there and have it shipped here for cheaper, go for it. Customs might be a pain in the a$$ though, i'm not sure.
Let me know if you need any more info about where to get stuff.
EDIT: I just called Grogro, and they don't really have stock of anything at the moment. They are going to be placing a new order for more stock soon though. I am not sure if they will be able to get comet TC's though, as there is a shortage since they closed. The guy says that the people that took them over have started production again of the old units.
Prices: TAV2 - R3000-00 ($444)
Comet 40 series - R4000 ($597)
Comet 700/800 Series - R6000 ($895)
Pretty expensive!!!!! He said he did have one or two secondhand units though. He only had the drivens for the 40 Series. They cost R2000 and the belts are about R500