A4C offers the Duracell Rechargeable Instant USB Charger, model no. PPS2US0001, for $9.95 with free shipping. That's tied with our February mention and the lowest total price we could find by about a buck. This portable 1150mAh Lithium-ion battery features USB and mini USB interfaces plus an on/off switch. It offers up to 35 hours of backup power and includes a USB to mini USB cable and power adapter. Deal ends May 9.