Factory Authorized Outlet via eBay offers the DuroMax 3,300-watt Gas-Powered RV Camping Portable Generator, model no. XP4000S, for $209.99 with free shipping. That's the lowest total price we could find by $80. Rated at 7HP, it features eight hours of continuous run-time, 4-gallon fuel capacity, and 3,300-watt continuous output (4,000-watt max).