I decided to add bluetooth capability to my 540 M-Sport. I bought the parts from getBMWparts.com (Tischer BMW) for what I think is a great price. Everything was plug and play on my car as the car was built with a Motorola phone installed. That means that it already had the SES module in the trunk for VR and a microphone in the overhead.
Below is the list of parts it took to do the job:
84109195455, TCU with bluetooth, $276.45 (after core return)
84506928461, bluetooth antenna, $20.60
51168215493, Center arm rest tray, $11.66
84136924546, TCU mounting bracket, $22.14
Ship & Handling, $28.90
Now I have a fully integrated factory bluetooth phone system installed. I paired it with my HTC Inspire 4G and it downloded my contacts without a hitch. I can now dial either by scrolling through the phone book on the MID and/or inst cluster or dial by voice using number or contact name. And.....the new parts have a warranty of two years, unlimited mileage.