AC Moore and Michaels usually carry it, too. I bought it at AC Moore in a roll.
I store my spellbinders in an Iris plastic case from M's. I put magnet strips cut to size on chipboard, and put the chipboard down inside the case. I have over 40 sets stored this way in one Iris case.
I use vent covers from Home Depot or Lowes too. I made my own book. I cut 12x12 heavy chipboard in half, bound it with my bind it all. Put the magnetic sheet down each side. Put dies on and used label maker and put labels down side. Now I can hold it sideways, look at labels, and find what I'm looking for. I keep all dies together. I have one book for shapes, one for alpha/border type and another one that is like circles, squares, etc. I covered front and back of each book with scrapbook paper, and I can tell the paper what's inside. They stand on my shelf. I need to take pics when room is clean sometime.