Don't buy it if you can't see it run, drive and LIFT. You should be able to find a decent running forklift for under a grand.
I bought a running propane Yale a while ago, (probably 50's or 60's). Payed $800, ran it for a couple years, and sold for what I payed for it. Restoring one would make no sense.
Another thing - there are NO parts, but you can sometimes cross-matching with generic replacements or adapt parts from other applications. Like mine had Continental engine, so was able to get some parts that route, and things like brakes can be cross-matched through NAPA. Here's mine(was)
http://img.photobucket.com/albums/v24/djenyc/forklift/IMG_0835.jpg[/I
Was kinda a pain to work on - engine compartmen is very cramped, hard to access components. I was using it for moving pallets, loading/unloading and stacking pallets on pallet racking - in the 2 years I had to replace - starter solenoid (was able to fit one from an old Civic), ignition key, several propane and oil hoses, brakes master cylinder, oil filter housing (could not find a replacement for the original oil filter). If anything big went - I would have to junk it.
If you just need something to move heavy machinery inside the shop - IMHO a pusher-type 12V pallet stacker might work better - lower maintenance, easy to maneuver and get in to tight spots.
I had this Presto 12V stacker:
[IMG]http://img.photobucket.com/albums/v24/djenyc/IMG_0743.jpg
and a Big (little) Joe lift:
A couple things on stackers - they are easy to push on concrete floor, but don't do well on asphalt, can't go on a grade, need clearance to get it's base under the load or need to go around the load (no counter-balance).
BTW - if you do get a forklift - guys on forkliftaction forum are great for advise - got me out of a few tight spots with mine.