I think BMWofsouthatlanat has it with free shipping, $439 or so (I think)

Install is pretty straighforward - harness is plug and play. You do need to have it coded for all features to work, but my recollection is that it will be NOT be fully functional without coding.

Oh, near unanimous agreement that the BMW harness is the one you should use- hitch itself there are multiple vendors, but the harness should be BMW (with oe connectors, etc)

GL