750$ seems to get you a complete kit off ebay, intercooler and all.
I'm one to piece together my own kit though. Some of the components in those ebay kits aren't worth taking the gamble on IMO. Especially the wastegate. A lot of the Chinese wastegates will fail, and they fail in a fashion that leaves them stuck SHUT... which isn't good. Google "purpose of wastegate".
Another option is using factory turbo coupe components, computer and all. That solves the issue of tuning for boost.
The tuning issue is the big one you need to worry about. Everything else is gravy.