Star-Doo via eBay still offers this 12,000mAh USB External Battery Pack
in Blue (pictured) or Pink, model no. PB-A408, for $15.98
with free shipping
. (Select each item to see this price.) That's tied with our mention from a week ago as the best price we've seen for any 12,000mAh portable battery charger. (Outside of the price below, it's also $2 under the best price we could find for a comparable battery pack elsewhere.) It comes with several adapters suitable for most types of charging ports, including iPhone, iPad, HTC, and other smartphones.
A close price: 2012FreeCompany via eBay offers a similar model for $16.14 with free shipping.