Figure "the usual suspects" replacement parts into your budget....
-Inspect driveshaft for forklift damage/dents - it's common to have to replace rear driveshafts (~$400-450 for custom rear)
-More often than not, you'll need to replace both batteries (tray fits Group 31 or 6TL. 31 is a more common size, figure $100-125 apiece x2)
-4 new (or good used) tires. Most of the tires they come with are over 10 years old - tread may look OK, but replace with new or at least <5 year old tires to be safe. ($0-1000)
-Oil change, check diffs and TC ($30)
-Inspect brakes, replace as necessary
-replace fuel filter ($19.98 for stock Stanadyne at Autozone or Napa spin-on conversion + fittings is under $50)
-New belts (?)
-Front axle spindle and wheel bearing inspect/ repack (mostly just labor assuming no bad bearings, special socket is about $20)
-License plate light to be legal ($10)
-New wiper blades or at least a bottle of Rain-X so once it's running, you can see where you're going in case it rains. ($5-20)
Even the "nice" ones tend to need a fair amount of parts replaced before they are truly roadworthy. Figure that they are all around 25+ years old so they're going to need some work. All the little Gremlins that were lying dormant on the GL lot tend to hatch out of their eggs once you rack up a few miles. Mine was running/driveable when I got it and I *still* had to work on it almost every day for the first couple months. Some fixes involved total rebuild, others only required minor inspection/adjustment. I've got a lot of hours invested in it, that's for sure.
Mine's a daily driver now, most of the bugs have been worked out. It's safe and somewhat reliable, but I still have a long list of things that still need work and improvements I'd like to make.