I hate to say "I told you so", but I warned about this last year (Check the posts).
I think prices are going to continue to slide because they have been artificailly inflated. The big investors are the ones who bid up the prices initially, causing the huge appreciations in value. But now that prices have begun to slide, and appreciation is negative, a lot of them are bailing, leaving only the enthusiasts, and the wanna-be investors who only have three choices: Keep the car, take a loss now, or take the chance of taking a bigger loss later on. As the economy weakens, so does demand for luxury items and risky investments. The only bright spot, is that the dollar is so weak, that foreign investors are becoming more interested in our vehicles. Unfortunately, that means that huge numbers of American muscle cars will leave our soil, and probably never return.