Warren Buffett once said the only thing he wouldn't sign is checks.
And it was true.
In the late 80s and early 90s, Buffett, who turned 94 on Friday, was a prolific signer.
He'd sign countless letters sent to his Berkshire Hathaway office in Omaha and it eventually became popular to have Buffett, once the World's Richest Man, sign money, ranging from $1 bills to uncut sheets of uncirculated cash.
At Berkshire Hathaway shareholder meetings before the numbers got out of control, Buffett would sign books and annual reports for shareholders.
But as Buffett got older, the supply of autographs started to dry up relative to the supply that should have been in the marketplace.
Market observers credited two factors: People who owned Buffett seemed to have flipped his autograph less than other celebrities and Buffett just wasn't signing much anymore. When annual meeting crowds turned into stadium crowds, getting to Buffett was nearly impossible.
"There's surprisingly very limited supply as it seems like, by the time people figured out he was a collectible figure, he had stopped corresponding through the mail and was aware of the market and reluctant to do anything for anyone," said Jeff Woolf, whose Iconic Auctions sold a $100 bill signed by Buffett last year for $6,544.
Want to just get a ground floor Buffett? An authenticated signature on a piece of paper or an index card will run you $2,000.
"He's the greatest investor of all time," said Buster Scher, a collector and well-known influencer. "He's almost like the only hero to people who are somewhat risk averse. He didn't bet it all or strike gold. His money just slowly compounded over 70 years."
Among the items in Scher's Buffett collection are three letters, including one sent back to a pastor who asked for a signature.
In April, Buffett collectors' heads turned when a set of six uncut dollar bills, which previously had sold in the $5,000 to $7,000 range, sold at Goldin for $20,700.
Darren Rovell is the founder of cllct.com and one of the country's leading reporters on the collectible market. He previously worked for ESPN, CNBC and The Action Network.
Darren is a Buffett collector. He owns what is believed to be the largest Warren Buffett signature in the world, nearly two feet long.