Walmart offers the Sportsman 4,000-watt Dual Fuel Generator, model no. GEN4000DF, for $229.98 with free shipping. (Amazon charges the same for Prime members.) That's the lowest total price we could find by $69, although most stores charge at least $500. It can run on gasoline or liquid propane and generates 4,000 peak surge watts and 3,500 rated running watts.