This one is hard to beat based on pricing/capacity:
http://www.merimobiles.com/cager-b03...p/meri7080.htm
They also have even less expensive models with solar cells and lower capacity lithium batteries. If you have enough sun and they're high output solar cells, a lower capacity battery may be more than enough if you can continue to recharge the battery... OTOH, that 10 Amp unit looks like a pretty good deal, if you don't need solar recharging.