iGeek 9900mAh External Battery for $40 + free shipping
ThinkGeek offers the New Trent iGeek 9900mAh External Battery Pack and Charger, model no. IMP99D, for $39.99 with free shipping. (The shipping discount shows at checkout.) That’s the lowest total price we could find by $9. (For further comparison, we saw it bundled with another battery pack and charger for $30 more a month ago.) It features two USB ports and is compatible with a large number of iOS and Android devices.