Ebay offers eBags Classic Shoe Sleeve 2-Pack for $8 (reg $19.99) with free shipping.

Product Description:
These shoe sleeves are designed to fit women's and men's shoes. Protect shoes and clothing from dirt and debris. Drawstring closure, versatile stretch panel and very light weight.

•  Wide open mouth for easy packing
•  Cinch tight closure with quick release button slider
•  Center panel is made of Lycra fabric for stretchy, versatile packing
•  Stretch fabric allows for packing of different shaped shoes such as, platforms, golf shoes or hiking boots
•  Soft design allows you to fit your shoes easily into small packing spaces
•  Women's heels can pack together in one bag, giving you a second bag for an additional pair
•  Men's shoes fit into individual bags, comfortably fitting up to size 13
•  Formerly known as Shoe Sleeves - Set of 2