This Intex Twin 8.75" Waterproof Airbed Mattress drops from $12.97 to $5 at Walmart.com. Shipping adds $4.97 or is free with in-store pickup. This is the lowest price we could find by $8. It features a waterproof surface, 300lb weight capacity, and measures 39"L x 75"W x 8.75"H. Sales tax is charged in most states.