My in-laws need to buy central air and gas furnace and have a licensed HVAC person to install. They don’t live here, so they just want to pick up the units. They want a name brand unit (Carrier, Trane, etc) and they want 4 ton with 16 seer for AC. The furnace needs to be gas with at least 80% efficiency. Does anyone know where, or even if it's possible, to purchase the system from someone without having to also pay them for an install?