Fans and collectors went mad for the card on which Potter author JK Rowling had written a short teaser about what will happen in the next Potter adventure, The Order of the Phoenix.
So far we only know that it contains words like "Ron... Broom... Sacked...Dies".
Among the bidders was the Potter fan website The Leaky Cauldron.
The website has spent the last week and a half appealing for its readers to donate money so that it could buy the unique message, and then tell its readers what it says.
Even though it didn't win, they're donating the £10,000 they raised to charity.
The proceeds of the sale, and the money from The Leaky Cauldron will go to a charity called Book Aid International.
They provide hundreds of thousands of books for children around the globe, particularly in some of the world's poorest countries.