I have a 1972 Plymouth Scamp that's been sitting for 25+ years, how much is it worth?

Please don't be upset with some of the answers. Our members are just trying to be honest. It's like trying to call a doctor on the phone and get a diagnosis on a difficult medical problem. He will politely tell you it isn't possible. He will tell he will have to see you and check you out. If he is honest, he might even tell you it could be something very bad, and that you need to come in right away. Well, we need to see the car and check it out also before we can give you the diagnosis (price quote) you want.
Before taking the pictures, you need to do the following things:
1. Roll it out, wash it thoroughly on the outside. If the paint looks pretty good, you might even try to polish and wax one place (like the hood or a whole fender) to show us how good the paint is.
2. Then clean it up thoroughly on the inside, and I do mean thoroughly. We need to see how the interior looks.
3. Thoroughly clean out and clean up the trunk.
4. Thoroughly clean out and clean up the engine compartment.
5. Try to get it running. It will be worth a lot more if it runs. It is not a difficult task. the gas in the tank will be garbage, so you will have to bypass that. If you have any questions, ask on this forum about a week before you try to start it.
6. Now you ready to take pictures. Take lots of pictures. If there are any bad places, make sure to show them. The presence, or absence, of tears in the interior, big dents or rust spots/bubbles in the body, the price will be affected. Crawl under the car and look carefully for rust anywhere. Rust in frame rails, floor pans, trunk area, etc will affect the price.

Then post the pictures. I do not know what the limit of pictures per post is. You might have to do it in two posts.
Then we can give you a better idea.