Amazon has 30-Gallon Fiskars Kangaroo Collapsible Garden Bag for $17.49. Shipping is free w/ Prime or on orders of $35 or more.

Features:

• 30-gallon pop-up gardening container with sturdy handles and tear and mildew resistant vinyl-coated polyester construction; Works well for cleaning up lawn waste, toys from the yard, or laundry from the clothesline
• Folds to 3 inches for space-saving storage; Internal spring activates to pop open when garden bag is ready to be used; Sturdy handles provide comfortable carrying and unloading
• Vinyl-coated polyester construction keeps leaf bag tear and mildew resistant through heavy use, makes cleaning easy, and provide excellent durability for lasting value; Fiskars lawn and garden tools are built to last
• Backed by full lifetime warranty