I'm inclined, really, to try my best to make my own sounds. Not only are there copyright restrictions against certain music ( actually probably all of the music I'd want), but morally I actually don't feel right taking someone else's work.
So I'm reduced to recording my own sounds: "Bwooosh" "woooooooeee" "Buuuuoooom"
Of course, this isn't really so great in a room with thin walls. I believe the neighbors don't appreciate all my hard work in entertaining them. Or maybe they do.