How much are you trying to store at one time? I got one of the 50lb "Vittles Vault" and it holds a 50lb bag (obviously) of feed. Super lightweight and keeps moisture out. I am horrified by the way some people store their horses' grain. Loose, in open bags, open garbage cans, etc. I know I'm paranoid, but I just have visions of opossums having a feeding fest every night and crapping all over the food.

http://www.amazon.com/Vittles-Vault-50-50-Pound-Stackable/dp/B0002DJOOI