We've been fulltime traveling for 13 years.  Between DW and I, we go through an average of 5 books/week, about 1/2 and 1/2 paper and e-books.  Haven't paid for any reading material since textbooks in college MANY moons ago.  As a couple of others have mentioned, the "secret" is libraries.  We have a 2" stack of library cards from all over the country, and that doesn't include the ones that have expired.  We still download e-books from libraries we haven't physically visited in years.  Out of 38 states visited thus far, only one has refused access to its' libraries.  Oregon's libraries are not long-term visitor friendly.  Seems to be a state-wide policy as we we have been refused in 4 separate locations.  If you aren't a resident there and can't prove it with a drivers license or similar, good luck.   
Hats off to the public library system in this country!