I'm looking at Gen 1's, as well. I want a 14' Screw (stock, blue w/ blue accented interior) with less than 50k miles. I want to keep it long term like my 80' Formula Firebird (parents were original owner). Figure I'm looking at $40k to $45k, depending on the milage.
I'd much rather be spending in the mid to low $20's, but that kind of milage scares the hell out of me. If the last time the owner replaced the shocks was at 100k miles you're probably going to need to replace them again. Not to mention, there is bound to be normal wear and tear replacements needed at that milage; the engine might be built proof, but not the rest of the thing. If you're good with a wrench and can do it yourself, go for it. If you're going to need a shop to make the majority of your repairs, maybe hold off and save some more for a newer, lower milage one.
Either way, best of luck on your search and keep us posted on how it plays out.