VCP will go back that far.
a 56 mantle in PSA 3 sold for right about the same in 2006 as it does today.
The real increase has been in higher grades. For example a PSA 8 sold for about 2200-2500 in 06 and today brings about 3k+
I think the trend is that higher grade collectibles are bringing more money as there are fewer of them around. I know its the case with comics and cards