Bought a $22 dial indicator holder off a guy at a flea market, and it earned its keep in one job
Cheap aluminum base with a busted clamp screw, but it held my indicator steady enough to show the vise on my mill was off by .011 over 6 inches. Boss wanted to buy a new Kurt vise, I shimmed it and saved him $600. What is the cheapest tool you ever bought that paid for itself in a day?
Something I read somewhere said the best machinists are the ones who can fix a problem instead of just throwing money at it. This is kind of the same thing. That whole "buy the fancy new part" thing is usually what people do first, but half the time a shim or a little tweak does the job just fine. Your boss probably would have never known the vise was even off if you had not checked it with that beat up indicator holder. Sounds like 22 bucks well spent to me.