I've got a 1980. Once upon a time it was a 301/automatic car. Now it's packing a Pontiac 400. I think it's much happier now. As to value? I don't really care, I bought it to drive, not as an investment.
If you're looking to make money, mutual funds are a better option than muscle cars. If you're looking to buy a toy to play with and enjoy, then forget the capital gains/loss issue and drive the thing!
I paid $1000 for my T/A back in 1999. But, these cars still had the "mullets, trailer parks, and trans ams" stigma back then and the owner was desperate to sell.
Matt