Tooth sticks and wood glue. Cheap and works perfectly.

Notched straightedge, fret rocker tool, action gauge, fret leveling file, fret crowning file… There are plenty of tutorials over there. Adjust the truss rod, level the frets and crown them. Then you can adjust the action as low as you like, without any buzz. These are the basics. Twisted necks are at a different level of complexity, but just having a good action without any buzz is a great achievement.

To me, this is a great opportunity to learn how to setup guitars. I did it a few years ago, after playing guitar for over 20 years, and it changed my life. Just need a few tools that can be bought cheap and, no matter how inexpensive the guitar is, it will play much much better.