Chris and Federico right, it’s the big heaters that will really cost you in the winter. I can’t resist though, I still use mine. Along with that, having a lot of computers and power-hungry electronics can consume a lot of electricity also. In the winter my electricity bill can be in the 300-400 range, but it’s shared between me and a single roommate.
I’ve tried space heaters in the past but they are either not effective or are burning you, in my experience. Never seen a gas/wood stove here (have you Federico?) but that would be pretty great. I’ve also fantasized about getting one of those standup gas heaters that they put outside of hotpot restaurants in winter and putting it on my roof.