What is an item below 100 bucks that everyone should own?

https://feddit.de/post/2136244

What is an item below 100 bucks that everyone should own? - Feddit

Stud Finder.

Knocking can get it done, but the surety of knowing is a nice to have for sure.

Do you have one you recommend? I bought one but either I’m not using it correctly(most likely) or it doesn’t work consistently.
I have a Bosch one from their professional range. Finds not only studs, but also wires, etc. Super useful, but expensive.