I agree with the main theme (that knowledge is often worth paying for), but you should be much more careful before advising technologies like Kindle which are heavily loaded with DRM and kill-switch. We all know how Amazon disabled all copies of 1984 from the Kindles once. The fact it was 1984 is a "funny" coincidence, but the point remain. Granting to a company (by itself, or because asked by a government to do so) the power to destroy all the copies of a book in the world in one click is not something we should do.

http://www.defectivebydesign.org/amazon-kindle-swindle explains it better than I do.

Until ebooks are respecting the rights and freedom we have with paperbooks (like a plain PDF do, but not a Kindle ebook), I would recommend to people to buy good-old paper books, even if they are a bit more expensive. Freedom is also worth paying for.

(Sorry if this is a bit out-of-topic, but it seems an important point to me; and yes I know that political arguments should be two-sided, there are positive aspects in Kindle and most ebooks, but I wanted to bring attention over a very negative aspect which is, IMHO, sufficient to overcome the positive ones).