It takes a long time and looking at the sales of a lot of Mustangs to understand value. After 40 years, two 66 mustangs that started the same are now quite different. #1 you have to think about rust. If you can weld, you can save a lot of $ and buy a car that needs some panels replaced. Most Mustangs need the cowl and floor pans replaced. After rust, then you can look at the drivetrain and interior etc. Mustang engines are on the cheaper side and easy to rebuild. I think the interior is easy as well and not too much money.
So it depends on finding the car that matches your skills and interest. If I buy another Mustang, I will surely post pics here and ask for opinions. Right now craigslist has a 66 shell for $800 and another shell for $10k. I think I probably just confused you more, sorry.
