With orders of $25 or more, Amazon offers the Relief Pak English 6" Ice Cap Reusable Ice Bag for $3.08 with free shipping. That's the lowest price we could find by $2. It features a large opening, waterproof rubberized fabric, and a plastic cap.

The Relief Pak English 9" Ice Cap Reusable Ice Bag is available for $3.75 with free shipping with orders of $25 or more also. That's another price low by $2.

Note: These are part of the Amazon "add-on" program and can only be purchased with orders of $25 or more.