[rarity + notoriety] x demand = price
I have lots of very rare but obscure cards. Rarity may be through the roof but notoriety and demand are low. This Ruth card is rare, with only a handful of known examples, but obscure:
A 1952 Topps Mantle is common--I could buy one within the hour if I had the scratch--so the rarity figure is relatively low but the notoriety and demand are way up there, so the price is strong even for a beater. Anyone want to swap the Ruth for a 1952 Topps Mantle?