Since the release of the first novel "Harry Potter and the Philosopher's Stone", the fantasy novel series has gained immense popularity and commercial success worldwide. The text from Wikipedia says:

As of June 2011, the book series has sold about 450 million copies, making it the best-selling books series in history and has been translated into 67 languages, and the last four books consecutively set records as the fastest-selling-books in history.

Now all the seven stories are available online for sale on Pottermore Store website. The site has been setup by the author J. K. Rowling in partnership with Sony.

All these eBooks are now also added on Amazon and Barnes & Noble. Customers can search for them in the company's respective store, but will be directed to the Pottermore Shop to register and buy them.

At the time, all eBooks and digital audio books are available in English only. But in coming weeks French, Italian, German and Spanish editions are expected with further languages to follow.

Price List:

eBookDigital Audio Book
Harry Potter and the Philosopher's Stone$7.96$28.70
Harry Potter and the Chamber of Secrets$7.96$28.70
Harry Potter and the Prisoner of Azkaban$7.96$28.70
Harry Potter and the Goblet of Fire$11.15$52.63
Harry Potter and the Order of the Phoenix$11.15$52.63
Harry Potter and the Half-Blood Prince$11.15$52.63
Harry Potter and the Deathly Hallows$11.15$52.63
The Complete Harry Potter Collection$61.65$266.98