Cost: $5,400 – $8,900, Installed. Average installed cost of a typical 3 ton, 2-stage packaged heat pump will be $5,700 to $8,000 depending on installation factors. Add-ons to improve air quality raise cost. These all-in-one systems are mostly installed in homes without a basement. The main factors that will affect the cost of your AC unit include home's square footage, desired brand, and the SEER rating you choose. For a 1,300 to 1,600 square ft home you would want a 2.5 ton AC unit and the average installation cost would be around $3,570 with the unit alone costing around $1,285. Read more about these cost factors below.