It's funny that the NADA pricing says the opposite..
That one on EBAY does not look bad, but to be honest I am having some issues with that color. It's one of the few colors I don't want--yellow, pink and the Sassy grass green. Sublime was better IMHO--but we don't want to get into a color rant.....
Take NADA and toss it.
Go get involved in the hobby, go to some bigger shows and see what cars are actually selling for. And buy one from a private party. Rather than a Classic Car Flipper that buys people perfumed pigs that no one would buy before until they got put in a fancy showroom, got glorified pictures, and some good old fashioned used car lot primping.
That 71 FC7 340 Challenger has non factory undercoating under it.
Is it basically restored to the fender tag? Do you know if the fender tag is real or not? Does it have a buildsheet? Do the numbers match the cowl and radiator support stampings?
Look at pictures of the inside of the rear quarter panels from the trunk to see if it has original quarters. Original quarters will have undercoating with a large square-ish block off region around the inside side marker bracket.
Sounds like a $22K to $28K car. It looks like a little more expensive car in the pictures, but there are corners cut that most of the time indicate that other corners cut that don't show up in pictures.