It is expensive, but I think you're underestimating the costs.
If the AC catches fire because your electrician skills are bad, what happens? I guess you can rent a ladder if you need one, but they're at least $200 if your split is on the second floor and ladders can be deceptively tricky, and load ratings must be considered. Condensation can kill you and be an extreme cost with mold. Your first mini split is going to take a real long time to install, I promise, assuming you size it right. There is a non trivial risk to life and limb.
This is one of those "Reality has a surprising amount of detail" things.
If you're not comfortable with the electrical work, hire an electrician.
Of course don't DIY it if you're not comfortable, but a simple exterior wall install is fairly straightforward. On a second floor install, (with the condenser on the ground) you only need a small egress hole you can drill from the interior. You'd need a ladder just to secure/cover the lineset.
Catches fire? The amount of electrical work with installing a minisplit is minimal. And HVAC technicians are not electricians, either.
The skill involved is that of tightening screws on screw terminals.
You're gonna plug it into the outlet? its going to probably need a circuit at the breaker.