I got the adapter from Morristown for $250. Install at the dealer was another $250. It takes 1-2 hours to physically install, no running wires, your SA just didn't know what the hell he was talking about.
The big thing is the programming ... I'm not sure, but I think (and I'm sure Jspira will correct me if I'm wrong) if your car is newer and the software is up to date all they have to do is activate it? If the software isn't up to date, they have to update that first. Which in my case took overnight.
I can understand a dealer not being that enthused about tying up a tech to babysit a software update for a few hours when the quoted install time is 1-2 hours.
I don't have idrive, but I like getting the id3 tags on the stereo. And I like being able to skip forward using the steering wheel button. But it is an expensive toy just for those few abilities.
If I were to do it over again, I'm pretty sure I wouldn't.
We're getting set to order my wife a Q7, and Audi's ipod interface is only $200. That seems like a no-brainer.