Sunvalleytek via Amazon offers the RavPower Luster 6,000mAh Portable Charger
in five colors (Black pictured) for $19.99. Coupon code "3H9TNEI7" cuts it to $9.99
. Plus, Prime members receive free shipping
. (Non-members can spend $35 or more to qualify for free shipping; otherwise, shipping costs $6.37.) That's $90 off and the lowest total price we could find. It features a battery status LED indicator and flashlight.