Factory Authorized Outlet via eBay offers the Duromax 8,000-watt Dual-Fuel Portable Generator for the in-cart price of $499.99 with free shipping. That's tied with our mention from two weeks ago as the lowest price we've seen. (It's also the best price we could find now by $270.) This generator runs on propane or gasoline and provides a constant 8,000 watts of power with a 10,000-watt max output.