Most Premium 7 radios (silver or black buttons, whatever those are called) have built in AUX in if you do not have a factory crummy ipod adapter (which you can't use to "line out" from Pandora/IHeartRadio) or an external CD Changer. It's pretty easy to install an AUX on these radios, even if you have the ipod adapter or CD changer and you're willing to remove it.
I had the factory ipod adapter and went back to using the AUX in. You just have to repin the harness.
A few weeks ago I installed a Dension Gateway Five. It enables bluetooth phone connectivity and A2DP Bluetooth Audio. So I don't have to plug in my phone to hear the audio, just to charge it (installed hardwired USB 10a Griffin charger in my center console for that). It's a good option for a couple hundred bucks.
If you want to go cheaper, you can try to install an aux to the factory radio. There's a dealer installed aux cable part number that is the pins on one end and a 3.5mm connector on the other.