My local library always has a section of books they are giving away for free.  Some of them are ones no one wants and some are priceless finds.  They make great presents.  They are also a good way to find out about something that interests you or peaked your curiosity.  I have found books on teaching kids to read, wars, romances, mental health, and a bunch of other topics.  Check it out.  Free is always good.  If your library doesn't do that, mention it to them.  There are always people with books to donate.