What is something really stupid you purchased that turned out far better than expected?
I bought a piece of 1.5 inch stiff foam to try to fix a sag in a bed. It didn't work but having that thick piece of solid foam around has been a life saver.
Need something flat to put a laptop on? Throw it on the foam. Going to be doing something that requires you to be on your knees for a while? Get the foam!
It went from stupid purchase to something I'd gladly replace if it broke.
Not quite the same, but my wife bought me one of those silicon rings for $35 because I was finding the metal one from our actual wedding to be too uncomfortable.
Love it and only thing I’m annoyed about now is how much I spent on the original ring vs this awesome cheap ring.