There are several fuel and heating costs calculators on the internet. Here is a great one provided by Travis Industries. Mazzeos retails Lopi Stoves and FireplaceXtrodinair made by Travis 

Travis Industries, the largest, privately owned wood, pellet and gas stove, insert and fireplace company in the North America..

http://www.travisindustries.com/CostOfHeating_WkSht.asp?P=2

(Be sure to include your delivery charges in the electricity rate as well as any other charges you are incurring with fuels)