Managing the lineset is the scary part (though it's not that hard). You're vacuuming copper lines that you've hopefully sealed correctly. If you get that wrong and your refrigerant yeets off into the sky, you have to call in help because it's hard for an unlicensed person to get the refrigerant legally. That half-hour of work and ~$1 of materials will cost you a punitive amount of money.
Ten years ago, I downloaded a free study guide and took the test in-person at an A/C supply shop for about $50.
Today, you can take the test online.
You do have to go through the permitting process which means having someone come out to view it and write off on it and if you state it properly it should be less than $200.
The actual work involved is relatively easy and straightforward. However, the code and regulations are extremely difficult to navigate. There’s a lot of non-obvious things you have to do to be code-compliant.