Different types of pens:
None terribly fancy, but I like the different feels of how they put ink onto pages. Between inking pens, gel, ballpoint, and the most recent fountain pen, they all just have interesting ways to move across the paper. But they quickly add up, even with cheaper pens, and I don't have the room for them.
Steam games (on sale):
Sales are my hell. Too many times I'll see a game for cheap and buy it, only to wait on installing it and simply forget that I've ever purchased it at all. It's sort've nice, though, because down the road I'll happen upon a gem sometimes! That's how I justify it anyway. Lel.