If you get a OBD2 328i and drop a T28 turbo (or similar) and exhaust into it, it'll be pushing around 300hp at the crank. For parts and labor you're probably talking around $5-6k, but that thing would haul ass.
Though if you're looking that hard for power, consider the E36 M3 (around the same years, preferably 95), as those are easiest to get to the higher HPs and they handle the power better.