Anythings worth is purely subjective. As was mentioned before, it's only worth what someone is willing to pay for it, and then, it's only worth that amount to the person that paid it. Is gas worth $3.00 a gallon? Yes, if I don't have any and can't get it cheaper anywhere else. It all depends on the circumstances.
I know I'll never get back the $8,000 I'll have in my Ramcharger, but I don't care. It'll be better than new and built for exactly what I want it do. Plus, it's cheap to insure and way cheaper than a new 1/2 ton truck. Of course that $8,000 figure covers only parts and materials and does not cover labor! I have not logged my hours because it's the "doing" that gives me joy, not the buying. I've had countless people wonder why I would put so much time into such a turd, but I just turn around and ask them how they spend thier free time. Usually it's "watching TV, going to movies, or sitting at a bar". "Well" I say, "It sounds like time well spent, what's your return on these activities?". That usually shuts them up.
Anyway, it is America and if someone wants to spend 100 g's (or 20 g's) on a /6 Dart, well, more power them i guess but that doesn't make that same car worth 100 g's to me. Cars will always fluctuate in value just like any other commodity, but I'm a bottom feeder and will always look for the best car for the least money that I won't feel guilty about modifying.