I bought the Metra iPod Adaptor from Techforless.com for roughly $35-40 shipped (can't remember exact price) a few weeks ago, and now its even cheaper. Install was easy and it came with an iPod mount.
The only problem is that when I connected my iTouch to the unit, the unit wants to control it but is incompatible. It will play my music, but when I go to music on my iTouch I get the "Accessory Connected" message, so I had to unplug my Itouch to change music.
Went and Jailbroke my Itouch today and got the noaccessorysplash app added to the jailbreak. So now I have regained full control of my Itouch and it only recognizes the adaptor as a dock, so I can control my music fully from the Itouch again the way I want.
Total cost for it all was under $40, and I have full control over my iPod with perfect sound, all out of the factory unit.