Wow, I was just on Auto Trader.com looking at these for some reason (thanks for putting that idea in my head Biggie! I'm using the Hall H1 as my desktop right now!)
Most of the '04's (I was surprised to find any--they are kinda rare) were going for upwards of $70-$75K. I did find an Alpha with 120K miles on it selling for around $89K, which was cool but wow, they drove the wheels off of it.
I've seen alot of really nice '02's going around your price range. I found a really nice '00 wagon here in town with a brand new engine (75 miles) and lots of claimed upgrades--he has it listed at $62K, but states he knows he won't get that much, but has much more in it than that. Come on, give me a reason to go test drive that H1!
http://okaloosa.craigslist.org/cto/2710963015.html
Also, here's my pick for a lower dollar clean looking '02--I'd actually consider picking this one up, the wife and I love the color.
http://www.mota.com/buy/listing/2002-HUMMER-H1/m8592f7
Good luck with the hunt---that's only half the fun!