Don't know if most of you already know or use this, but a while back, I found this service called
Bookbub (
https://www.bookbub.com/home/). It is free, and once registered, it emails me daily a list of the "deals" at Amazon, Kobo, and Apple iBooks (these deals don't last very long, from what I can see).
Via this, I've found some good digital books that I really enjoyed reading (e.g. The Mistborn Trilogy which was free for a time at Amazon.com -- a value of $24 CDN -- I really enjoyed that series). Not all books that I've found for free via this site are great, of course, and many are the first of a series, but still, there are some good catches there, and a nice way to try out books at no cost (or little cost). And I still buy certain specific books, but still, this is, to me, a good additional resources for books.
I don't know if it works in other countries, but it works for me in Canada and presumably also in the US.
-D