mine this month is 860 units, $133 + $100 for the lines co, so $233 all up. Wish i could pay $160 for 700 units, but we get extra ripped off here thanks to seperate bills for the lines. I worked out the most my tanks could use is $60/month, thats 5 heaters and a couple of lights, filters, assuming that the heaters run 2/3 of the time. Biggest cost is the oil heater to heat the house, we don't have a drier.