[kelnos]

This kinda sounds like the installer had a queue of much larger / more lucrative projects to tackle, and quoted you a high price to get you to go away... or pay the ridiculous price and make it worth their time.

A decent heat pump sized for that square footage should cost well under $10k, and it's pretty unlikely your house would need so much work to install it that the labor involved could make up for the rest of that quote.