I paid $2500 a few years ago each for very simple 1 outdoor/1 indoor unit , wall mount outside and run straight up the wall to an outside wall. I ran the electric to the outside wall. This is for the Fujitsu RLS3H. all sizes (9/12/15) cost about the same. I expect prices a bit more these days just because of COVID, etc.

This single unit pretty much heats our entire home 1800 sqft well insulated and sealed. We have a tiny 11k btu Rinnai in the basement which I really like to have for backup.