On the card side, T206s are very common. But it is precisely the prevalence of T206 cards that breeds T206 collectors. You need a reasonable supply to generate conversation between collectors. That's why I got into autograph collecting -- but only the T206 guys. Collecting rare baseball autographs of players not associated with classic baseball card sets is not supported by a lot of interested collectors.
Relatedly, the setting of prices is driven by competition for items. But nobody knows how high to bid when there is no existing market. That’s why I spend a lot of time trying to educate collectors about the relative scarcity of T206 player autographs.
A popular Brooklyn Superbas from years gone by, but only because of the T206 set...