Some of the newer HU have BT and usb built in .
I wonder if you have one those features are its just not turned on .
There is or was I guy on Ebay selling the new OEM head Units without most BUS for around 325 and the ones with most bus for around 450.
If you have a USB Port on the back of the radio you might already
have the capability for USB and bluetooth its just not turned on and you don't
have a microphone .
This doesn't get you A2DP as far as I know you can only get that with a combox and you must have idrive at the same time.
http://www.e90post.com/forums/forumdisplay.php?f=27
above is wrong one I think
http://www.e90post.com/forums/showthread.php?t=687463