I think the market is disproving all the disapproval about muscle car values. It's classic "supply vs. demand" at work, just this time it's not about gum scented pieces of paper with ballplayers on it or some pulp magazine introducing a rich guy that likes to fight crime dressed as a bat.
BTW, the same can be said about the mega-million values for the Ferrari GTO or the 300SL Gullwing . . . you could have bought either for a song back in the sixties.