A lot of the things that make a baseball card valuable make sense -- better condition translates to the higher prices, for example, and cards depicting hall-of-famers yield more than cards immortalizing choke artists.
But just as many factors make no sense at all. Relatively common cards can sell for more than rarities in the same series. Pristine selections can sell for multiples more than the same card with a barely perceptible blemish. A particular card might develop such an interesting story that aficionados can't help but put in a bid when it arrives on the auction block. "It's all about what collectors perceive as being desirable," says Joe Orlando, president of Professional Sports Authenticator, an organization that inspects sports collectibles for authenticity and grades their condition [source: Orlando].
And collectors are willing to pay a lot for what they desire. One key obstacle to definitively listing the world's most expensive baseball cards is the fact that many private collectors make purchases without the particulars of the transaction ever being published -- and the prices they pay can be far more handsome than any of the figures made public. "I can say for a fact that in the last year, more big records -- six- and seven-figure records -- have been set privately than publicly," Orlando says [source: Orlando].
So, with these caveats in mind, let's look at five of the most expensive baseball cards in the world.