Read your meter, and look at your most recent electric bill. This will tell you exactly how much you are using.
Two additional ways to calculate cost:
You can find out the exact amount of electricity used by each heater with a Kill-a-watt meter. ($25 at Amazon.com)http://www.amazon.com/P3-Internation...9681973&sr=8-2
IF the wattage of the heater is listed on the unit, you can calculate electric usage assuming the unit is on 100% of the time. For example:
600W * 24 hours /1000 (kilo) = 14.4 KWH per day. At 10-cent per KWH, that heater costs $1.44 per day.
Ask your HVAC person about the age and efficiency of your existing furnace. (They measure combustion efficiency when they service the unit, they should have this on file). If efficiency is less than about 80% you will want to replace.
I think it may be well worth your time to call local community agencies and see about possible financial help or loan programs for furnace replacement. LIHEAP and some charity programs are listed here:http://liheap.ncat.org/profiles/Indiana.htm
With the weatherization program, it does not matter how the house was purchased or financed.