You probably won't see many LFS carry them. They need daily rinsing to keep them alive long term. Dead ones in the batch can spoil all of them. Most stores see this as too much work, while some stores may not even know what you are talking about. If you use them, you would be better off ordering them. That way you would get fresh ones. It's not recommended you buy more than you can use in a week or so however, and I wouldn't feed them everyday. Fish that become "addicted" to them sometimes refuse all other food.