BMW actually do not make one and it was going to be a problem for myself -
instead I bought a new E65 730d SE so the problem was solved for £55K.  

The only part available from BMW is the BT aerial.

Can I suggest that if it's that important go to a reputable BMW wrecker and get
the complete thing from a newer car and fit that after removing the BMW/Motorola
crap and freeing up the storage drawers that are pretty useless anyway.

A better alternative is to buy one of the snazzy BT kits with a touch screen
which, I believe can be used as a sat-nav or Speed camera detector but perhaps
this is my imagination or wishful thinking.

BTW - if you have the Sat-Nav (standard I think) then you'll need the v 3.0
software update and I can get you a modified 2008-01 DVD with all euro & GB
speed cameras and full 7 digit UK postcode search - you will need the v 3.0
software update.

If you are interested then personal email for details as this is not the place.