In my opinion it is impossible to know with any shred of certainty without seeing more photos, or seeing it in person. For a Jeep that old, I would generally assume it's worse than what the seller is admitting to, therefore even a $500 offer is a risk.
"I give you a republic, if you can keep it." - Benjamin Franklin
I would be figuring in the $300-$500 range if even that if not running. From the pictures looks like you might only end up with a grill, hood, and title. I never believe anyone that the frame is good until I crawl under there myself. For $1500 I would expect something that can move under it's own power at the minimum. A lot of these people only know it is an old vehicle and to them that means it's worth money. Unfortunately even a fully restored Jeep will usually be worth less than an un-restored popular muscle car.
I own a Harley and a JEEP, still some people can't figure out why I'm broke!