Action gear via Amazon offers the Enercell 3-in-1 Portable Universal Combo Car Charger, Wall Charger, and Power Bank in Black / Silver, model no. 2301756, for $7.38 with free shipping. That's the lowest total price we could find by $9, outside of the mention below. It features a 1,350 mAh cell capacity and supports most portable devices with USB.

Of note, Alta Tac via eBay offers it for $7.99 with free shipping.