Another couple of alternatives.
http://tinyurl.com/kvxxsc5
5VDC - 15000mAh
8VDC - 8500mAh
12VDC - 65000mAh
$36.90 free shipping
3 different voltage outputs from the one battery.
http://tinyurl.com/kwyd5af
12VDC - 9800mAh Li ion
$43.69
This one I have and is quite good. I will now make a couple of adapters to suit.
These from dealextreme.
Great company to deal with.
Thanks for the idea Phil