The Noontec Powa 10,000mAh Power Bank w/ 2 USB Ports & 30-Pin Cable drops from $99.95 to $15.97 at Yugster. Shipping adds $5, but this was still the best price we could find by $19. This compact, lightweight back-up battery can charge an iPhone more than 5 times, and can charge two devices at once. It also includes a Micro USB cable for charging and a 30-pin adapter for Apple products, and it comes with a 1-year Noontec warranty. There's no sales tax (except UT).