The Guardian recently authored an article on whether or not further books in the series get a limited or even get printed due to ebook privacy. I am firm believer in a artists getting their fair share for their creative efforts and pirating ebooks does have an economic impact.
If the financials cost your concern a great source of free and legal ebooks can be your public library. The ebooks are accessible via your library card and be downloaded from anywhere onto your smartphone or tablet.
Both allow you to download ebooks directly to your smart phone or tablet and are great source of content that simply part of public libraries’ offerings.