eCase via Amazon offers the Kmashi 15,000mAh Dual-USB External Portable Battery Pack in Black/Red for $15.99. Coupon code "WG5DWJHV" cuts that to $12.50. Plus, Prime members bag free shipping. That's tied with our March mention, $37 off list, and the lowest total price we could find. It features a 2-amp USB port, 1-amp USB port, status LED lights, and microUSB cable.