exhaust can be easily fabricated, say you'll have about $100-150 in the custom down pipe, and to have the crossover pipe custom made, I'd say anywhere from $50-200. I cant remember how banks had their crossover and up pipe made, but the crossover into up pipe is where it would get expensive if you had to have that made as well.
Turbo's are delicate pieces of equipment, but it doesnt take a rocket scientist to rebuild one. If the wheels are damaged and it has "in-out" play then I'd junk the center cartridge and get a new or reman one from banks. If you get a new or reman CHRA, it'll already be assembled, and all you'll have to do is install the housings onto the cartridge.