AnkerDirect via eBay offers its Anker PowerHouse 120,000mAh Portable Outlet for $499.99. In cart, that falls to $349.99. With free shipping, that's tied with last week's mention as the best price we've seen for this model. (It's also $100 under what Amazon charges.) Features include a 12V car socket, 110V AC outlet, and four USB ports.
Reviewing this critical insurance policy takes a little effort, but it pays off big.