Harry how bout this - pay somebody to develop the specs, including pipe
layout, sizes and locations for intake and vent - then use your
"Muscle" and install the sucker yourself. I got a quote on a new HVAC
system installed with high efficiency air for around $7K for a 2,400 sf
1 story structure. Some parts of the country have really pricey HVAC
contractors - lots of demand now. At least get a quote from a good
installer/dealer and get an idea of about how much you could save - you
might find out your time is more valuable than your savings on a hourly
rate.