Posted By:
Eric BrehmKing -- I think your observations are probably correct. I suspect that set collectors go after not only what they can afford, but what they can reasonably expect to find.
Actually your data shows that population is a pretty good predictor of price in this case:
PSA 7:
avg pop ..... 49/19 = 2.4 ......... '52 Topps commons are 2.4 times more plentiful
avg price ... $165/$70 = 2.6 .... '33 Goudey commons are 2.6 times more expensive
PSA 8:
avg pop ..... 30/14 = 2.13 ........... '52 Topps commons are 2.13 times more plentiful
avg price ... $425/$200 = 2.14 .... '33 Goudey commons are 2.14 times more expensive
Granted there is a lot of data being averaged here, but I think it is striking how closely the relative scarcity of cards from the two sets matches the price differential between them in each grade. It suggests that the relationship between scarcity and price is roughly linear.