Factory Authorized Outlet via eBay offers the Duromax 8,000-watt Dual-Fuel Portable Generator for an in-cart price of $499.99 with free shipping. That's tied with last week's mention as the lowest price we've seen. (It's the best price today by $621.) This generator runs on propane or gasoline and provides a constant 8,000 watts of power with a 10,000-watt max output.