The factory controlls cant be directly connected to most headunits, they CAN be used with any aftermarket headunit that comes with a wireless remote, the part you need is called PESWIX-IR to interface your factory controls to an IR signal.

The factory interface can be adapter with some patience, a little solder, and spliced RCA plugs. The guy as best buy was an idiot.

You will need a headunit with 3 preamp outputs and it helps to be able to disable the factory amplifier to reduce heat output. The kenwood mp4028 has 3 outputs at 4volts and a wireless remote. you can also disable the built in amplifier and it runs $150. I have the MP4028 interfaced with the PESWIX-IR for my factory steering wheel controls and it works flawlessly.

The total cost for your install shouldnt exceed $300 for parts and labor.