Been looking into a few things and found a few sites that may be of interest.
This one sounds interesting and was wondering if anyone had any experience with their products.
Anyone with any experience with Goal0 units like the 150W SCOUT PAK w/30W MONOCRYSTAL FOLDING PANEL(Goal0) ??
This looks like a decent unit for camping or emergency use.
I have been searching extensively for the last few days for the best solar charger without braking the bank, and it seem that Goal0 makes the best product for the price.
You can get the entry level 7w solar panel from Goal Zero for $63 online, that will allow to charge most usb devices and it also has a 12v output.
Keep in mind that is way more powerful of most of the chargers mentioned above but it doesn't have a buffer battery, which means that no sun no charge.
I'm pretty sure you could remedy to that with a backup battery, so you could charge your battery during the day and be able to use the juice harvested at night.
I'm considering getting the goal0 7w panel in conjunction with a Proporta 5000mah usb battery pack, i should be able to get the whole kit for around $100, also for a little over $30 I could get a AA/AAA Goal0 charger to work with the solar panel.
As a disclaimer I'm not affiliate with any of the company I mentioned or I consider myself an expert on the topic!