Raymond Hekking spent decades trying to convince the world that the Mona Lisa painting he bought from a French antique shop in 1953 was the real thing and the one in the Louvre Museum was a fake.
Now Christie's auction house has put the 'Hekking Mona Lisa' up for sale, hoping the story of his campaign to realise his dream will help compensate for the fact it is a copy.
"It looks like the Mona Lisa but the quality of the execution is not Leonardo da Vinci," Christie's International Director of Old Master Painting Pierre Etienne said.
"Unfortunately on that point the dream is a bit over."
Hekking's argument was that the original painting was never returned after an early 20th century theft, ending up in the shop in the village of Magagnosc in his native Provence while the gallery in the French capital was duped by a copy.
Numerous newspaper cuttings testify to his badgering of the media and a Pathe newsreel item from the 1960s shows US journalists turning up to inspect the copy when the actual Mona Lisa was loaned to the United States.
The painting was done by an unknown artist in the early 17th century, around 100 years after the original by the Italian Renaissance master entered the royal collection of Francois I, Christie's said.
It has a guide price of 200,000-300,000 euros and the online auction ends on June 18.