If you want just a good ol’ fashioned heatpump for vents you can’t go wrong goodman, at least from an old reliable standpoint. Not the most efficient i find, but reliable, cheaper than the ones with their names branded on the side, and easy to get parts for.
If you are looking for the HE ones the research has been a bit of a tossup between how handy you are and vs how much of a dumb version you want. We ended up with the AQI extreme temp line and are diy-ing it as the tools needed to connect yourself are about $150ish and can be used for flaring lines in vehicles we fix. If i was not so handy or confident, take a look at Mr Cool brand as they are the easiest to diy if you aren’t comfortable drawing down vacuum lines or flaring lines.
We got our from hvacdirect dot com but i can’t say if they were the absolute cheapest, I just gave up shopping around.