I've been doing some checking, and it looks like the unit with everything that I need (bezel from www.mybimmer.net, Sirius tuner, iPod hookup, and bluetooth) should cost right about $2200. Cosider this: you get more than just the nav part, and if you install it yourself, you get a really sweet custom install.

Also, one very minor mod and you get the full touch screen access through an on off switch so that you can stay "legal" in states that prohibit some types of mods.