For me, it was a pair of merrell shoes on sale. They have lasted 3+ years, have great grip in the snow and ice, and so comfortable, my feet don’t hurt after wearing all day.
Never cheap out on anything that comes between you and the ground; shoes, tires, a bed.
What have been some of your good purchases under $100?
This is going to sound silly but I’ve heard some people aren’t aware you need to open it and take the plastic off the internal diluted before first use. Did you do that?