Zionsville is the most severely overpriced cooling system parts for our cars EVER. And that's saying a lot, a whole lot. Zionsville is cool though in that they allow you to run all the factory hosing and even make an all-metal thermostat housing. However, there are other tig-welded alternatives. PWR makes two thicknesses of radiators for like 480-500$. If can fit the thicker one, I would definitely run it, I don't know the difference between the two and what fan/condenser combo will work with the wider radiator. If possible, I would try to stick with the factory plastic electric fan, it has a factory interface for the computer. I know that it does fail, but mine has been great, I've witnessed some pretty horrible stuff caused by one of these fans fail, I've also heard of fires from their control modules.
For the pump, either stock factory replacement, or emp stewart.
For the housing, either stock or zionsville.... which i think is like $500+
2001 330ci TT turbo
1992 240sx coupe
1999 328i nachtblau