Max Tool via eBay offers the DuroMax 3,500-watt Hybrid Dual Fuel Propane/Gas Portable RV Generator, model no. DS4400EHF, for $449.99 with free shipping. That's the lowest total price we could find by $100. It features a 4-gallon fuel tank, 4,400W max capacity, 3,500W rated capacity, and up to 20 hours of run time.