The books are available in English (US and U.K. edition), with Italian, German, French and Spanish editions coming in the following weeks.
J.K. Rowling's Pottermore site is currently the only place where you can buy the books. The rest of the site, which will combine elements of a Harry Potter-themed game and social network, is still available only as a beta version and due to fully open up in April 2012.
The ebook versions of Harry Potter novels were originally supposed to be made available in October 2011, but the launch was delayed as the site was struggling to cope with overwhelming demand from beta users of Pottermore.
The books are available in EPUB and Amazon Kindle formats, and also as audio books.
The prices for the first three novels in ebook format are £4.99 ($8) and £17.99 ($29) for the audio books. The next four books are £6.99 ($11.10) and £32.99 ($52.70), while the entire collection is available for £38.64 ($61.70) or £167.34 ($267.40), respectively.