ipod ready alpine radios only require a $30 cable. other brands such as sony, pioneer, and JVC only charge $50 for the interface. Kenwood is the most expensive at $100. I dont know about you guys, but I care about controling my music from the radio and charging the mp3 player at once. Alpine has a great ipod interface, and using an ipod is the only way to control and charge your music from the radio. I can throw my ipod in the glove box and listen to whatever I want without touching the ipod. Not all ipod interfaces are made alike. Alpine makes the easiest to use interface, followed by pioneer, then kenwood. The sony ipod interface really sucks, and I haven't tried JVC's, but I would use a JVC radio anyways.
People can complain about ipods all they want, but they have the most aftermarket support. You can get anything to pug into your ipod! the best you can find for other players is a leather case. Yes I hate itunes, but other mp3 players have nowhere near as much support. If it matters any I didnt buy my ipod. It was a christmas gift from my girlfriend.