Condition, condition, condition...
"typical rust" will drop the value of a rig $2k-3k IMO, even some minor rust easily drops it $1000-1500 or more. Take a $4k 60/62 with some minor rust on the front doors (at the W/S), some minor rust on the rear hatch (around the glass) and some minor rust in the license plate light of the tailgate... and it would cost you $1k-2k to fix, or more. Starts making a $5k-$6k "no work needed" legitly clean 60/62 worth it.
I can pick up a running/driving 60 here in town for $750-2k all day long, a couple a week at that. But the bodies are junk, the frames are pretty sad in the rear and they would need alot of drivetrain service just to bring them around. Legitly clean rigs here in SLC demand a premium, not uncommon to see a clean 62 sell for $5k.
Don't do the work yourself? A knuckle rebuild can cost $1k at a shop, a motor rebuild $4k, even a simple brake job $500. Consider all of that when buying a used rig... ask for service histories, pay a shop to do an inspection of it, or check it our really well yourself.