So many options available from a wide range of prices. The low priced cast wheels are from China, even American Racing...
What you might save on a low priced wheel designed to fit a late model BMW, you probably make up in money with spacers, plastic hub centric rings, etc. Also, remember that you have a long front hub that probably won't work with a center cap on a BMW wheel. This will require an even bigger spacer and now longer studs. That suddenly puts you in the range of a nice set of custom built wheels in the design and fitment you want specific for your application.
Wheels are the one item I feel make or break a car as far as looks.
If your set on doing this than look for BMW M5 wheels as they're low offset.
Good Luck!