To most people in the industrialized world, Bill Gates needs no introduction. Microsoft's chairman has been one of the richest people in the world for nearly two decades, and he has held the title for wealthiest overall on numerous occasions. As of March 2011, his approximate net worth is said to be $56 billion .
Gates has not been shy about purchasing items that can be described as "big ticket." This includes one of Leonardo Da Vinci's few surviving scientific journals, which he purchased at a 1994 auction for almost $31 million . Rather than keep it to himself, he had it scanned and made its contents available to the general public, who can buy it on CD for $30, or less than 0.0001 percent of his original purchase price.