I asked my neighbor who is an HVAC guy and runs his own business. He said "If somebody offered to do it for $400, he should jump all over it", he said he usually takes his total cost to install the system and subtracts the cost of the new equipment at wholesale price. Said he'd be a lot north of $400 to do it. I know nothing about any of it, I just happened to remember your post and saw him standing there so thought I'd get an opinion for you. Good luck!