Thatdailydeal offers Dual USB Waterproof Solar Cell Phone Power Bank for $9.49 (reg $34.99) plus $2 shipping.

Product Description:
Keep in mind, this will recharge slow with the solar panel, so while it's great if you're in a pinch without power, it recharges much faster via USB
This is a waterproof 5000mAh solar charger, which comes in a variety of colors. It also comes with a top-head flashlight, 1A and 2.1A ports, 4 LED indicator lights, and comes with additional accessories, including a mountaineering clip, a USB-to-micro adapter and one 4-pin adapter. Compatible to any phone as long as adapter has a USB head. Outer-casing is shockproof rubber that secures charger while water-resistant tabs help keep it safe from water. Great for outdoors and useful in most conditions.
Features

Size: 5.5" x 3" x 0.5"

Weight: ~7oz

Solar Panel: 1.2 W

Output: 5V 2.1A

Input: 5V 1A

Durable, waterproof, shockproof

Compatibility: All smartphones