Upgrading to SAT NAV is it realistically possible?

I know I can just go buy an after market touch screen nav system for my accent. But Im a guy whom likes to keep things OEM for later resale value.

I can buy the NAV unit off of a junk dealer (wrecked car) or off of fleabay. My question is, since these cars already have the antenna due to XM, would there be much to installing an OEM touch screen NAV unit? Or would a whole other harness be needed?