There are massive government grants right now. First thing to do is read this page and start following it's steps.
ecoACTION - ecoENERGY - ecoENERGY Retrofit*– Homes
it looks like from the feds alone you can get $790 for the right gas furnace. $500 for air source heatpumps including minisplits if you have 1 head unit per floor.
$4375 for a ground or watersource heat pump if you live somewhere it's viable.
here's the grant table.
Grant Table | ecoENERGY Retrofit – Homes
I bought 2 years ago just as the program ended. Had I had an inspection before it did I could have gotten a few grand back based on what I already did. Taking my attic to R60 cost me $700 and was worth $750 back...