How much does it cost to run 24kWh on my diesel generator?
The generator you linked to claims to need 4 gallons of fuel to produce 9.5 hours of power at 2.5 kW, or 23.75 kWh.  That is about 6 kWh per gallon.  At $ 4 per gallon, your fuel cost is about 67 cents per kWh.

In other words, you would spend about $ 16 per day on fuel to average 1 kW.  That cost does not include lubricants, maintenance, depreciation, nor the hassle of refueling the generator on a daily basis.  In most places, this fuel cost is much more than the retail cost of the electricity produced.