Hobby Lobby and Ben Franklin Crafts has hinges if you have one near you.
Ihe first time I tried to add hinges, I was thinking like hinges on a door and didn't realize the hinges I had were meant to be installed flat against the *ouside* of the back of the box I was making. When I went to the Rockler website to look at their hinges, I saw a picture. DOH!
It was still a problem as the screws were too long for a 1/4" box that had been sanded to a fraction smaller than that. A wire cutter fixed that but I wish the screws that came with the hinges were a little shorter.