I picked up a solar charger at Costco (U.S. brick and mortar store) for $59. It's a clever design with the 3 wings that open up. It'll soak up the sun and charge my N800 at the same time.
http://www.solio.com/charger/

It came with 6 or 7 electronics tips, so I can use it for all my gadgets. We're planning a safari for next year, so one of these solar chargers is essential.