We did a DIY install a few years ago. Cost about $4500 in total for a Bosch 18k BTU unit and everything needed to install it.
We got $900 back from the state (WA USA) and $2000 back from the feds. That brought our total out of pocket down to $1600.
We had electric resistive heat and no AC previously. Our heating bill went down by $50/month in the winter. It added maybe $10/month in the summer for air conditioning.
For our area, with mild winters and low electricity costs, it's fucking amazing.
I'm a mid-career mechanic in the USA. I found my last job on Indeed.
There were TONS of mechanic jobs available in my area (Seattle). I was able to be really picky.