Target has the 2-Pack 5-Gallon Household Essentials Wide Hanging Shelf Drawers for $4.29 with free in-store pickup or free shipping on $35+. One storage bin measures 7.75" H x 11.75" W x 11.75" D.

They're made to be used with the Home Essentials 3-Shelf and 6-Shelf Hanging Closet Organizers, but they can also be used by themselves.