If you buy a cheap turbo kit the following will happen 99% of the time:
1. Your turbo will fail within a few ours or few weeks.
2. Your turbo manifold will crack.
3. Your couplings will suck.
4. You will re-buy 90% of the components that came with the kit because they suck.
5. You will skimp on tuning & crack a ringland on your stock motor & have to rebuild it.
The list goes on...

Do it right or don't do it at all.