Sunvalley Brands via Amazon offers the RAVPower 10,000mAh 2-in-1 Wall Charger and Portable Battery Pack in Black for $29.99. Coupon code "DELPB066" knocks it to $22.49. With free shipping, that's the lowest price we could find by around $12. It features dual USB 2.0 ports and is compatible with most devices. Deal ends May 20.