At Albertsons in their bakery they have buckets they get their frosting from. When they are empty they get rid of them. If you are at the store stop by the bakery, and ask if they happen to have any empty ones they have not gotten rid of yet. They will give them to you for free. They are food grade buckets so you can rinse them out and put grains or whatever in them. They also stack nicely, our girls like to use them out in the yard.
Thanks Kim for this Thrifty tip!