I'm usually really good with money... at least in real life, where I'm stingy until something good comes up.
But in games? Man, I usually save up all my money for seemingly no reason. Though usually that's because most times you get currency you're playing some form of RPG, which always means that give yourself a few levels and everything you just bought has become completely obsolite.
I remember one time recently in Final Fantasy XI, though. I finally bought myself a specific dagger that was really good that I probably should have bought YEARS ago. And then as soon as I bought it, they raised the level cap (after 7 years of not ever doing so, go figure) and it became worthless again. Replaced by-- get this-- a dagger you get free of charge! And not only that, but it upgrades with each increase to the level cap so once you buy it once you're set for life.