Staples offers the Altec Lansing 1,500mAh Battery Case for iPhone 5/5s, model no. 3934824, for $6.49. Plus, Staples Rewards members bag free shipping. (Not a member? It's free to join.) That's the lowest total price we could find by $15. It features short circuit and over-charge protection and adds up to seven hours of talk time or 166 hours of standby time.