I have read posts saying some people had increases in their electric bill and others saying they have not. I guess it depends on where you live and how large your home is, how much your power company charges, whether you have electric heat or gas etc. We have a large home that is drafty with high ceilings, and so anytime I turn the central heat thermostat down several degrees when it is cold, it does help reduce the power bill even if I have the Duraflame heaters on.
We have 2 Duraflame heaters and we love them. One is in the family room and one is in the bedroom (although sometimes I move them around). I have not noticed that our power bill has gone up because of them. But I don't have them on all the time. I usually have the one in the family room on usually only in the evenings, for 4 or 5 hours and we turn it off when we go to bed. The one in the bedroom, I usually go turn on in the evening about a half hour before we go to bed, so the bedroom can warm up. Then I turn it off before we go to sleep.
The past week when it has been a bit colder in the mornings I have moved the heater from the bedroom into the breakfast room and turned it on while DH and I ate breakfast. The breakfast room is beside French doors and big windows beside the patio and it is very cold out there and the breakfast room is cold sometimes. The Duraflame heater makes it warm and comfortable for us while we have breakfast on very cold mornings. Whatever we spend on running the heaters are more than worth it to us. We like the warmth of the heaters and the ambiance of them. Even if they did raise our power bill a small amount, we would not mind because we really enjoy them.