This Mota 2600 mAh Smartphone Battery Stick with Optional Accessory Bundle drops from the retail price of $80 to $19.99 with free shipping at Groupon Goods. This is the lowest price we could find for these portable battery packs by $18. The single 2600 mAh battery stick has a built-in flashlight and is compatible with micro USB, mini USB, iPhone/iPod 30-pin connector, Apple Lightning, and PSP 3.0mm charging cords. You can also add $5 and get the bundle version, which includes an additional carrying sock case, wall adapter, and a charging cable. All colors but Blue are available and sales tax is charged in some states.