Equipment Costs. The average price for a new gas furnace ranges from around $2,300 to $3,000 depending on manufacturer according to a November 2012 article by Consumer Reports. Qualitysmith.com estimates the cost of a new electric furnace at $1,000 to $1,500 as of December 2012.lectric space heaters all have AFUE ratings of 100 percent. Assuming an electric heater with 100 percent efficiency, homeowners should expect to pay roughly $34.32 per million BTUs of heat. Natural gas is generally sold in therms, where one therm is equal to 100,000 BTUs.