Does an ex-wife count as a purchase? (LOL)
I have found it is the stuff I have longed for years, that fails to work well for me. I bought a bulldozer after years of wanting one, and it was a real let-down. It just was not big enough, and what I really needed was an excavator. (My tractor can pull and push, a bulldozer just pushed a little better. I need a machine that digs and lifts...an excavator!)
But it can be simple stuff too. Like when I did woodworking, I thought a planer gauge would be awesome, then I got one and never used it.
It is for these reasons that I have really become a minimalist. I do some really nice carpentry, and yet only use a skillsaw now...no sliding compound miter saw, no tablesaw, none of that stuff. I have just adapted to use less, to still get stuff done. It is unAmerican I know; to be contented with what I have that is, and make the most of it, but I am NOT materialistic any more.