Poweradd Direct via Amazon offers Prime members its Poweradd Pilot X3 10,400mAh Dual-Port Portable Battery Charger for $22.99. Coupon code "NBX883SL" drops it to $18.99. With free shipping, that's the lowest total price we could find by $9. (Non-members can spend $35 to qualify for free shipping; otherwise, it adds $5.60.) It features an LED flashlight, LED battery charge/discharge indicator, and two USB charging ports.