High Efficiency Furnaces. Prices Comparison. We take the confusion out of buying new furnace or upgrading to a new one..Replacing a furnace can be a very expensive but very important ordeal in the life of a home owner, and even more important if said homeowner lives in a cold climate during the winter!.The cost to Install a Gas Furnace starts at $, $, per furnace, but can vary significantly with site conditions and options. Get fair costs for your SPECIFIC project requirements..Compare Gas Furnace Prices, Repair Installation Costs. Gas furnaces are one of the most popular, effective, and cost efficient ways to heat your home during the winter months..