Hello!
I made my dividers with craft mesh, used for cross stitching with yarn, and the file spines for book reports. It was super easy, and for both dividers it was well under $5! The craft mesh you can get anywhere that they sell yarn just about, but you may have to go to an office supply (like staples or office depot) for the file spines, i just happened to have them laying around from when i was in school. ^^;

Gizmothefreaky, I noticed on a thread that you had a photo of a ten gallon, with two dividers, so it was in three.. Where did you get those dividers?