I recommend you stay away from that unit. Alot of people have had problems with it. They tend to get discs stuck in them. I thionk it would be better to go to Walmart and for $100-110 buy the 10 disc changer and mount it in the hatch/trunk. Later if you upgrade to a nicer HU, you can still use the changer.
If you must have one, post a WTB ad, or try ebay, I see them there all the time.