You guys may be surprised at how reasonable OEM parts are from the main dealer parts counters. Admittedly i have only been doing this with Mercedes, but despite them being a monumental rip off for actual services, their parts dept is almost as reasonable as any of these online outlets. Its nice to get the official parts receipt for your service history, and know that the parts are 100% OEM.
I am about to pick up another BMW at the weekend, i am not sure how their parts dept are, but i am hoping for similar.