K.M.
What about introducing him to a new book series. You can go to Barnes and Nobles online and look at the different series they have to offer for his age. If you know what he may like you can read about the different series that hey offer. You can buy him 1 or 2 to get him started to stay in your budget. A few that I know that have been enjoyed by my son and nephews are:
Eragon
Seven Sleepers
Midnighters