BodyGuardz Armor Carbon Fiber Protection for 11-Inch Apple MacBook Air (2013), Black (BZ-ACBA1-0713) $ 7.09 & FREE Shipping on orders over $ 25
This item is available because of the Add-on program
The Add-on program allows Amazon to offer thousands of low-priced items that would be cost-prohibitive to ship on their own. These items ship with qualifying orders over $ 25. https://www.amazon.com/gp/product/B00ELPHTG8
Edit: Looks like you have to click through from the appleinsider.com page to get this deal.
"What’s more, each $ 1,799 MacBook Pro qualifies for free expedited shipping to the lower 48 for fast delivery to your doorstep within 1 to 3 business days. And since B&H will not collect sales tax on orders shipped outside NY and NJ, many shoppers outside those two states can save another $ 140 on average. This offer ends Sept. 10 or while supplies last."