That's one way to do it. I literally just finished building my own BT music streaming kit for my car, because I didn't want to pay Pioneer $400 plus for a plug in option.

I turned one of these, a Nokia BH-503...
http://www.nokia.com.au/MEDIA_BANK_1...03_312x312.jpg

...into this:
(whole unit)


(inside)


(controls on my dash; skip/track back, play/pause, skip/track forward)


(controls are backlit with blue leds)