Thats a $620 piece at the dealer (check prices at getBMWparts.com)

So I'd recommend you go the eBay route as I'd mentioned above and just buy this for $200:

Repair Kit For MKIV DVD SatNavs fitted to BMWs 2001-6 - eBay (item 110390972292 end time Jun-15-09 11:01:57 PDT)