I bought my H1 off of ebay. You can find them as well at www.dupontregistry.com
I agree with the guy who says to check cv boots, and how the transmission shifts.
Definately buy the Diesel......the torque output is higher, you'll get 10 times more life out of a diesel and their are lots of modifications you can do to diesels , these days.
Don't buy a H2 or even dumber an H3. I call H2's "Hahoes" because their a Chevy Tahoe frame, engine, chassis, suspension , with a funny body on them. Their in no way a real "Hummer". H3's are even less of a tahoe, they're
formed off the old small Jimmy & S-15 blazer etc.
I would steer away from a Humvee ( military hummer ) , because you know that 1. it's been beaten to death before the government wants to sell it, and 2. unless you only want it for hunting , etc. their are no creature comforts ( leather seats, airconditioning, stereo's , etc.
I bought my H1, for $ 65k then sunk another $42k into it, with the custom paint, engine mods, snorkel, McIntosh Stereo, 3 DVD's, racks, etc...