1939 Joe DiMaggio single signed baseballA Joe DiMaggio single signed Baseball is worth between $400.-$600. Value is based on average prices of recently closed auctions. Prices may vary based on condition, and the type of authenticity that accompanies the baseball. Signatures that have not been properly authenticated could sell at half the market value or less. If the ball was dated and inscribed by Joe DiMaggio "1939"it will have added value or if it can be authenticated as such.