Sunvalleytek via Amazon offers the RAVPower 26,800mAh 3-Port Portable Battery Pack in Black, model no. RP-PB41, for $49.99. Coupon code "PB41DELS" cuts it to $39.99. With free shipping, that's the lowest price we could find by $10, although we saw it for $10 less in February. It features 1-, 2.1-, and 2.4-amp outputs.