For my family storm kit I have a very large kit I got from Galls. For the kit in my truck I use a fishing bag that I got at Wal-mart for $25. If you buy from Galls and the like you are going to pay way too much.
I like the Flambeau bag in a prev. post. A similar bag from Galls will cost you four times as much and the only difference is a reflective emblem.