Technically the transmission and fluid are considered 'lifetime' by BMW which equates to 100k miles -- but I have been contemplating doing one on my car anyways. My local BMW dealership quoted me ~$650 for the job but I also have a good relationship with my advisor. If you're thorough with the job, the parts are about $580. I'm not sure if this is the exact parts list that BMW would replace/change during the service though.
