Onan states 1/2 gallon per hour so for us about a $1.65 per hour with $3.30 a gallon last time I gassed up. We use an inverter to watch tv, dvds, and HD satellite using the generator primarily for our high amperage items such as microwave-convection, AC unit or a couple of portable heaters depending on season, and heated appliances including those for hair.
We camp off the grid more than half the time and having the genny ready to power our entire rig with a press of a button makes for worry free fun. Average about 100 hours a year and don't give much thought to fuel costs, nothing beats being fully self-contained and the peace of mind that comes with it.
