Although a signed first-edition copy of his second book, "The Audacity of Hope," fetched $2,500 at a Signature House auction in April, Obama's signature is worth about $150, The Chicago Sun-Times reported Sunday.
"He's young. He's going to be signing a great deal. He's still not president," said Daniel Weinberg, who appraises historical documents and signatures at the Abraham Lincoln Book Shop in Chicago.
The newspaper reported that signed copies of "The Audacity of Hope" and Obama's other book, "Dreams From My Father," sell for $100 to $300 on the Internet auction site eBay, while baseballs signed by the Illinois senator go for $50.
"I don't think Barack Obama's signature is worth all that much yet," said Leslie Hindman, president of Leslie Hindman Auctioneers. "It may end up being worth a lot some day."
Even if Obama wins the presidency, the more he signs, the less valuable his autograph becomes.
Former President Jimmy Carter, for example, has signed so many books, his autographed works fetch $50 to $75, Weinberg said.