Well, there's a 1994 EBay with 80K or something, opentop for BIN at $29,000
Here. But it also looks like it's in very good condition with a well-kept interior and a new diesel engine. Has a 12,000lb winch and doesn't say anything about rust....
So what you're looking at, it has less miles but it sounds like it's got too much work to do. Your estimate sounds about right.
KBB is suggesting about $25,000 for a vehicle in "fair" condition matching what you've given. It could be "poor" depending on how bad that rust is, what the title looks like (salvage,flood, etc.), and that interior work.
If you haven't purchased the vehicle yet do some online research. I think from what I've read that (I think) pre-1997.5 A/C systems can be hard to fix. Plus a maintenance record is important to make sure someone took care of it (which it sounds like they beat the crap out of it...). If the CTIS is busted, it sounds like it would be an expensive fix to me.
I'm not an H1 expert, but I wanted to share what I've come up with in research, since I'm also looking for an H1. Good Luck.