17: Ford Mustang (1965-1978)
Where do we start with the Mustang? It was the car that started the entire pony car segment. The original Mustang was compact, fast, and offered great styling. But the Mustang is simply vastly overpriced right now, and part of that is because of the current classic muscle car bubble. Prices are going crazy across the board, and the original Mustang, while a classic muscle car, is not worth hundreds of thousands of dollars.
The car had a lot of reliability issues and early examples of the car are often in bad shape. Body rusting is also a very common issue that tends to affect the first-generation Mustang as well. If you can find one for a reasonable price, which is hard to do, the first-generation Mustang is a steal. Otherwise steer clear of this one.