I use http://www.bmwmercedesparts.com/partlocator/index.cfm?siteid=215771 exclusively. They are a OEM dealer and are much less than my local BMW dealer. For example, called local dealer on an oddments tray to replace my ashtray...local dealer wanted $72. Husker BMW wanted $23 for the exact same part. I have ordered quite a bit over the last year and all their parts are OEM.
Those are good prices. I looked at rotors 34116855153 list 84.82 getbmwparts 67.86 bmwmercedesparts 58.99 I wonder how different their shipping is?
Many BMW dealers charge ABOVE BMW suggested list prices (all the while calling this "list") everyday. Suggest using Husker Auto Group (BMW OEM dealership in Neb). These folks will give you 25% off actual BMW list prices everyday. Get your part numbers from realbmwoem.com and contact them through their internet site. Have used for many items with good success and you do not pay sales tax!