Check with Wheels America. They have locations in at least Grand Prairie Texas (Dallas suburb) and Houston. I saw a guy take at least an inch CHUNK out of a Z3 rim and they fixed it and I couldn't tell where the damage was...all for $99! It was amazing.
Another reply was right, they might have problems matching color, but I doubt it (the only problems I have heard are on the newer BMW M car rims).
I would put the damaged (then fixed rim) as the spare (check it often to make sure it is holding air) and put the "spare" in place of the damamged rim.
I have dented two of my rims, the size was about the size of the thumb nail. Both rims were fixed (polished) and the cost was about $60 each (one dent is smaller which cost a bit less). The result were ok. You can't see it unless you watch closely. They could not match the original finish, because the graphite polished weheels has the unique circulated tool marks on them. The best they can do was polish the area to blend in with the rest of the wheel.
You can also find the wheel repair shops at the back pages of the auto magazines and the cost is about $100 each plus shipping.