I put in an alpine DPR-RDS1
http://www.crutchfield.com/p_500DPRRDS1/Alpine-DPR-RDS1.html
I'm happy with it. It is an FM modulator that connects inline to your antenna similar to the porsche branded product. Sound quality is similar to your strongest FM station. Can't beat it for $99. It was easy to install, so you could find someone to do it way cheaper than the dealer. Oh it does connect with the ipod/iphone connector not the headphone style plug you were looking for.