Harbor Freight has a 2000 watt inverter for $500 thats decent. Those inverter units can adjust the engine speed to the load so they are crazy efficient. So if your just running a low load device it will run the engine at like 1200 rpm instead of 3600 at full load. All the larger generators run at a fixed 3600 rpm and suck down gas. A 6500 watt generator will go through a ton of gas often 5-10 gallons a day.
Those ecoflow and anker solar battery packs are also pretty awesome. I got a 2kw one at Costco that can run pretty much any 120volt device. It will power a fridge for 24 hours and they can be charged from a generator, solar, car, and regular ac outlet.
These 2 devices are like less than $1500 as well.