I have a well cared for Clarion CX609 Head Unit from my JK, ready to drop right into your JK!! Everything you need to hook it up is included (JK adapter harness, PAC harness which is required for Chrysler vehicles, antenna adapter, Metra mount kit for JK dash). All the wiring is done, so you just need to pull your stocker out, plug in the connections on the harness, and bolt the new unit in place. You WILL have to remove the radio support beam to fit this head unit, which is not terribly hard. 4 bolts and a little finagling.
The CX609 has a 25x4 amp, which will GREATLY improve the sound in your Jeep, but it will expose the pretty terrible quality of the stock JK speakers. So, you'll probably end up upgrading them as well. You DO NOT need an external amp with this head unit, it is loud and clear, even at highway speeds with the top down. An amp will only improve things, but it is not needed. With a good set of speakers and some time spent tweaking the sound settings, you will be pretty impressed.
This head unit has Bluetooth (microphone included) and will integrate your iPod, so you can control it from the head unit itself.
Here's a pic of it installed:
Clarion CX609 CD receiver at Crutchfield.com
ASKING $150 for everything, shipped to your door.
Please keep in mind that I had the standard audio system from the factory, so I'm not sure if it will plug right in to the Infinity system. If you have the Infinity system, please understand that I cannot guarantee you won't need a different harness.