You just never know, I run my 500wt heater, 75gal filter,10gal filter, powerhead, 2 air pumps, and run my AC or Heat all day for under $60 each month in 2 bedroom apt.
If the room is kept at 80-85, then the cost shouldn't be too high. The heaters are the main cost of your setup and you've got it covered already. Eheim 2217 is a pretty power efficient filter.