It was a new house (about 3000 sqft), so here's what they installed:
-6 wells @ 150' deep each (totalling about 2000' of pipe)
-All new ductwork
-6 ton unit
-"Desuperheater" for hot water
Cost ran me about $26k. A high-efficiency propane split system (1 unit in basement for basement and 1st floor, 1 unit in attic for 2nd floor) was quoted at about $24k.
I wanted to comment on the wells. Around where I live they drilled though 150' of dirt, gravel, and sand. They didn't hit any rock or anything special. The well was bored about 6" diameter. They didn't use any casing or anything. As soon as the hole was as deep as they wanted, they inserted the plastic piping then backfilled the entire well with a bentonite slurry. They did all 6 wells in one day.