We move so much right now that I don't keep a lot of books. Anything I buy, I pass on to someone else to avoid having to lug it around in a suitcase from country to country. Before we moved overseas, I used the library to avoid paying a fortune for books that I can get for free.
When I move into a settled home, I'll have to debate between buying all my books so I can keep and display them on some pretty bookshelves, or still using the library and saving space/money by not buying and storing books.
We'll see!