I've ordered a couple things from theBMWPS before and the service has been great and shipping cheap (USPS two day for $6.xx). Shipping depends on the size of the items of course.
I just finished an order on valve adjustment stuff and a couple interior items for the 330i since I was removing the homelink for the M and the mirror motor for the driver side mirror.
The mirror motor arrived with a ripped ribbon cable due to movement while shipping. The box has a portion that is supposed to keep it stable, but those cables are very brittle. I sent an email to Sean (customer service rep helping me with my order) with pictures explaining the situation and asking how to proceed. He replied by saying he just personally packaged and sent out a replacement with return shipping label. I received the replacement in a few days and it was packaged with some additional bubble wrap inside to keep the motor stable.
This was excellent service from a great OEM parts supplier in my mind. Hope others give them a chance and see the same service.