NuTrend offers the A-iPower Gas Powered 3,500-watt Portable Generator, model no. SUA4500, for $309.99 with free shipping. That's the lowest toal price we could find by $30. It produces a 3,500-watt running power and a 4,000-watt surge power. It runs for up to 13 hours at 50% load and features a 4-gallon fuel tank.
Update: Specs corrected.