Yugster offers the Noontec Polo Apple-Certified 5,200mAh Battery Pack in White or Green for $7.97. Coupon code "FreeYugBuck" cuts it to $6.97. With $3 for shipping, that's the lowest total price we could find by $3. It features two ports to charge any device via mini USB.
The countdown timer on the product page does not reflect an actual expiration time and resets daily.