Some of the people reading this list have zoned out ever since we mentioned that a single baseball poster was worth over than $60,000, because they've been waiting to find out what their baseball card collection is worth. After all, if a basic paper poster is worth so much money, a well-cultivated collection has to be worth more. That's logical - but it's also why it isn't always the case. Plenty of people collect baseball cards, and so the average value isn't that high.
The real value in a baseball card collection comes in rare individual cards; the sort that nobody picked up in the year they were issued, and have become harder to locate in all the years since. At the top of that list is a 1952 Mickey Mantle card, which a determined collector will pay over $400,000 for alone if you can supply it. Almost half a million dollars for a piece of cardboard. Madness.