I just visited one of Costco's Clearance Outlet stores nearby, and found this LiPo battery pack for $12! Just because it was out of it's packaging!
5v 2.1A out, wich charge level meter on front panel. Weighs about 12oz...
Had to buy two of them IMMEDIATELY before someone came to their senses!
It retails at Costco for $40, which is still a great price for LiPo 8000mAh here in Canada.
I suspect this will run my RPI and a pair of arduino's for most of the day... Separate battery for motors and servos...