Im using the Bosch LH 2.2 system from a Volvo 240 and it runs great. The MAF (mass airflow sensor) has a correction screw on it so you can adjust it till itruns correctly. The volvo uses 19lb injectors so I just used smaller 17lb ones but might go a but smaller since my engine was stock. But over all it was a simple installation. And you can use the LH 2.2 for turbo applications. Just swap the ecu and injectors and that's pretty much it.
Cost wise, this is how I broke it down
318i manifold, tbi and fuel rail $100
Volvo 240 wire harness, MAF and ecu from junkyard $75 to $100
Fuel system maybe $100 forget a 318is fuel pump assembly