3 gallons a day x 30 days is 90 gallons x $4 is $360 a month. We are renting a lot in Yuma for $250. Our last electric bill was $70. We have 2 Olympian catalytic heaters which we hardly use, and a small cube heater in the living room and a small toe kick heater on a thermostat in the bedroom. Bus was converted in 83 and not intended for use in cold climates so insulation is not that great. We get along just fine on what we have and have the freedom to head for warmer weather when it starts getting cold out......if we see frost, it is time to go! Only have 2 bays and fulltime so space is a valuable commodity for us, have no desire for a heating system, especially when every year i see all of the problems you guys have with them.....not to mention the initial cost, operating costs, and repair costs.