Publishers weren't very optimistic about the future of Harry Potter and the Philosopher's Stone when they printed it in 1997. Only 500 first edition copies were made, 300 of which were donated to libraries. As anyone who's been to a bookstore, movie theater, or theme park in the past two decades knows, that prediction couldn't have been further off.

Book one of the Harry Potter series spawned one of the most successful literary franchises of all time and earned millions for author J.K. Rowling. That means those rare first edition prints are exceedingly valuable today, and one of the most pristine copies ever discovered just sold for $56,500 at auction, BBC reports.

The sellers, an anonymous couple from Lancashire, England, had stored their copy of Harry Potter and the Philosopher's Stone—along with a first edition of Harry Potter and the Chamber of Secrets—in a code-locked briefcase for safekeeping. The plan wasn't to wait for the books to accrue value over time; originally, they had wanted to protect them and pass them down as family heirlooms.

The couple changed their minds after learning that another first edition copy of Philosopher's Stone had sold for $35,000. That turned out to be a smart move. By locking it away, they managed to preserve one of the best first edition copies of the book experts had seen. The book also contained two errors that made it an even more appealing item for collectors. Its value was placed between $30,700 to $37,000.

At the auction, however, bidders blew past those numbers. It sold for a winning bid of approximately $56,500. The buyer will end up paying $70,000 in total to cover additional fees and taxes.

That's a significant amount to pay for a book, but it's not even the highest figure that's been bid for the title. Earlier in 2019, a first-edition print of Harry Potter and the Philosopher's Stone with several errors sold for $90,000.

[h/t BBC]