Gamesalor via Amazon offers the Dual-USB Output 5,000mAh Rechargeable External Battery in White for $21.97 with free shipping. That's $2 under our February mention and the lowest total price we could find for this battery in any color by a buck. It functions as an emergency backup power source for cell phones, tablets, and other devices. It includes adapters for Sony Ericsson, Apple, Nokia, Motorola, LG, Samsung, HTC, and more.