The Most Expensive Book

Since I had written about rich people, let me follow it up with something a rich person might buy.

Codex Leicester is a collection of scientific writings of the famous Leonardo da Vinci. It became the most expensive book in the world when Bill Gates bought it in an auction for $30.8 Million.
Then came Tomas Alexander Hartmann, a German philosopher. The author of a 13-page book called 'The Task' (aka Die Aufgabe). It took him 30 years to finish the book and is only making a single copy. He priced his book at 153 million Euros (approx $235.16) making it the most expensive book to date.

The difference between Codex Leicester and 'The Task'? The Codex got to its current price by bidding in an auction, meaning (rich) people are willing to pay that much money to own the book. While The Task's price was set by the author itself. The reason for the high price being, according to the author, is that it took him 30 years to create the 13 page book plus there will only be one copy.