I'd look around on the larger enthusiast websites that have local or regional sections on them... particularly of higher end cars or cars that generally have more passionate owners. As for price that's going to vary a lot depending on how much you want done, whether you drop the car off or they come to you, how good the detailer is, as well as how large your vehicle is. Plan on a couple hundred bucks though for a "full" detailing inside and out that'll take about 6 hours give or take.
Couple examples for the Atlanta area after a quick search of a BMW forum:
http://www.detaileddesignsautospa.com/
http://www.peachstatedetail.com/
I could make this post a lot longer, but I'm trying to keep it short.
