i looked up the value of my car on nada a couple days ago. 5xxx on the low end 19xxx on the high end. for a hardtop. middle price was about 11xxx and they wanted me to subtract 10% for my rare, collectable, OHC 6cyl.
if you like this car, it may be worth 20xxx, but for 15xxx, you would like it better. you'll have to spend a couple grand for a good paint job anyway, not to mention all the rubber rot on a 35 year old car.