TomTop offers the Docooler Outdoor Portable Air Lounger / Sleeping Bag in Black for $12.99 with free shipping. That's a buck under our May mention and the lowest price we could find by $10 for an item shipping from the U.S. It features a 441-lb. capacity.
Note: It's also available in Rose, Burgundy, or Purple for $13.99 with free shipping via coupon code "SLEEPBAG2". Also, Nitwy via eBay has it for $5.57, with free shipping from China. It may take two to six weeks to arrive.