As of July, 2014, a Mickey Mantle autograph is worth anywhere between $300 to $50,000. There are many factors that go into estimating the value of both sports memorabilia and autographs. These include the signature condition, specific item signed and whether or not the item includes a letter of authenticity.
As of July, 2014, Mickey Mantle autographed items include baseball cards with printed signatures for $300 to $350, a New York Yankees autographed hat for close to $1,800 and an autographed baseball for $1,200.
According to Leila Dunbar of Leila Dunbar Appraisals and Consulting, a very expensive Mickey Mantle autograph was appraised in 2008. That year, the ball, signed by Mickey Mantle, Babe Ruth and Roger Maris, was worth $30,000 to $50,000. The key to this item’s value was the condition of the signatures of all three players. Additionally, this is the only ball known to be signed by all three players.