I'd rather get a single DIN head unit and a seperate portable GPS device like the Garmin iQue 3600, that way you can take GPS into whatever car you want and wherever else for that matter.
You may want to check out this nav buyers guide from caraudiomag.com. Most of the systems there are probably going to run you more than $1200 though. Definately check ebay as you can get some decent deals. I did some quick looking and for that price you might be able to go with the Kenwood kvt-617dvd (which is the screen I just put in) and the kenwood nav module (KNA-G510).
Hey Kevin: I have a 6 disc cd changer/navigational unit with a 5 inch screen. Would you be interested in buying it? I could let you have it for less than half the price mentioned above... email or respond if you're interested. Peace.