Power-innovation via Amazon offers the Maxboost Ambrosia 2400mAh iPhone 5/5s Battery Case in 27 colors (Green Eyed Envy pictured) for $29.99. Coupon code "AQBHSKWU" drops it to $9.99. Plus, Prime members bag free shipping. (Non-members can spend $35 or more to qualify for free shipping; otherwise, shipping costs $6.25.) That's $90 off list and the lowest total price we could find. This two-piece sliding case comes with a micro USB charging cable and audio jack extension.