Also look at Bavarian Autosport online at
Bavarian Autosport. They'll ask for your year and model of BMW. Then simple find the part you're looking for (it's easy to look up parts). You'll see a picture of the part, the part number, and how much they will charge you.
I just replaced the front right grill on my '94 325i and it only cost $20.95...a very reasonable price. I'm pretty sure the part was original BMW also.