Ending today, newegg offers the Timbuk2 Crater Laptop Case for 11" MacBook Air in Blue, model no. 393-11N-2211, for $19.99. Coupon code "AFNJ0936" cuts it to $9.99. With free shipping, that's the lowest total price we could find by $20. It features high density foam plus crater holes which protect and allow your laptop to cool.