Please visit this thread, as it is the most recent thread on this topic.
http://www.e90post.com/forums/showthread.php?t=483
I can't remember which thread it was where I first read someone asked about what you just posted. However, I do remember someone from England I believe posted that they talked to someone at their dealership and that person was told the headlamps were a one piece unit. And to replace one (with the Xenon HID lamps) was about $2400 USD, if I'm remembering correctly. Basically, it was real expensive. Also, this is a topic a lot of US buyers have been concerned about, so you're not alone in wanting the clear headlamps.