How much electiticy costs to run small RV heaters?

Nobody knows what electricity costs where you live.
However, an electric heater uses 1,500 watts. You have 3 of them? that's 4,500 watts. If they run for say 6 hours a day that's 27 kWh. Where I live electricity is about $.12 per kWh. So, that would cost me $3.24 a day. That's $97 per month.
I'd be complaining too if you were using that much electricity. The bill for my 1,600 square foot house with a family of 4 is only $84 per month.