Sunvalleytek via Amazon offers Prime members the RAVPower 3,200mAh Lipstick External Battery Pack in Black, model no. RP-PB08, for $17.99. Coupon code "S2M6KI2N" cuts it to $11.99. Plus, Prime members bag free shipping. (Non-members can spend $35 or more to qualify for free shipping; otherwise, it adds $6.18.) That's a buck below our mention from three weeks ago, $12 off, and the lowest total price we could find. It features a built-in flashlight and compatibility with a wide range of devices (including the iPad, iPhone, and Android phones and tablets).