I have been quoted £202 by Bahnstormers Maidenhead and plan to have mine enabled with the next service.
For any of you who may be interested, and particularly with the spate of BMW thefts, they are also doing a branded BMW Tracker. I understand, like the Nav V / V1 it is made by someone else and branded BMW. Retail is £345. However also check out Autocom who are also now doing a Tracker
I did read somewhere that this may be a BikeTrac rebrand