A Ty Cobb baseball card more than ONE HUNDRED years old just sold for -- are you sitting down?? -- a whopping $504K!!! ... TMZ Sports has learned.
The card is Ty Cobb's 1915 Cracker Jack card ... and it's one of only three of its kind to ever receive a Mint 9 rating from PSA ... which is just one step below the perfect Gem Mint 10.
If you think coughing up half a milli for a baseball card is insane, just remember the Honus Wagner card holds the record for most expensive baseball card at $3.