eCase via Amazon offers Prime members the KMASHI Mini 2,800mAh External Battery Pack with Light in Black, model no. KMAX-807, for $3.99 with free shipping. (Non-members can spend $35 or more to qualify for free shipping; otherwise, it adds $6.18.) That's $6 under our previous mention and the lowest total price we've seen. It's compatible with devices that charge via USB and purports to provide 1,000 charge/discharge cycles.