Bobby Livingston of RR Auction in New Hampshire said Clyde Barrow's .45-caliber automatic and a .38-caliber revolver Bonnie Parker had strapped to her leg were the last weapons the pair carried with them before they were shot dead in a police ambush in 1934.
"It doesn't get any closer than this for collectors of history," said Livingston, who will preside over the sale of the guns and other memorabilia from the infamous couple Sept. 30.
"This is one of the finest Bonnie and Clyde collections you will ever see," Livingston told CNN. "We expect the guns should sell anywhere between $100,000 and $200,000. But really the sky is the limit for these types of guns."
Britain's The Daily Telegraph said Livingston's optimism was based on the $210,000 apiece two other Bonnie-and-Clyde guns sold for earlier this year.
Bonnie and Clyde gained a cult following during the Depression by their seemingly unstoppable streak of bank robberies at a time when banks were not particularly popular among hard-pressed Americans. A new generation discovered their legend in the 1967 hit film "Bonnie and Clyde" starring the glamorous duo of Warren Beatty and Faye Dunaway.