https://www.harborfreight.com/3500-Watt ... 017a&sfid=
This looks like a pretty good buy. It is not 240V as usual but does provide two 120V circuits at 15A each, 30A total. 11 hours @ 25% load. Translated, that is 11 hours at 750W on 2.6 gallons, which is 1/4 gal per hour. Seems to be more aimed at RV power but it's still a generator.
It also supports parallel operation like the Hondas. If only these did 240V...