We are negotiating on a house and need to have a reasonable number for a new furnace that must be replaced in the upstairs of the new house. The entire house is 3000 sqft with dual climate control with two furnaces in the house. I assume that the upstair furnace will be responsible for about 1500 sqft and we have been told around $5000 for both the furnace and installation for a good furnance? Does this seem right? Does anyone know a site that compares cost? We live in the SouthEast part of the US. Thanks for the help..