In early 1990s, he changed focus and sold his huge collection.
Earlier, he sold his African collection for the same reason.
He later sold his collection of more than 1700 coins in 1866.
"It's a slow process because you've got to sell your collection at the end of the day," he said.
In 1912, he sold his collection to the University of Chicago.
It seems the Prince got a letter from a woman wishing to sell her late husband's collection.
Born and raised in California, she sold her first collection in 1990.
In auctions last night and this morning, she was selling her entire collection of about 300 photographs.
He sold his collection of eighty 1920s and 1930s motorcycles in March 2003.
He produced and sold his collection from this competition.