So far I've installed a stock 05 Touchscreen NAV and replaced my old Alpine XM with an XM Direct kit that interfaces directly with the new NAV - no more RF stuck to the dash!. Now I'm searching for a good iPod adapter, and maybe a Bluestar, then a back-up camera, and mybe an Xbox 360...
I got the Nav #15230099 from Craigslist $400
I found a GPS antenna on ebay for $75
The GM XM Direct kit #XMDGMK from a local stereo shop, the guy who ordered it couldn't pay once it was installed so I got a deal - open box for $100
On a side note I also picked up an Edelbrock cat-back exhaust for $135!!!
http://store.edelbrock.com/5737exhau...6hummerh2.aspx
Sounds great and was super-cheap!