I am looking to do some prototyping of audio games.  Do you have any suggestions for free or reasonably priced sound libraries that have a decent variety of sounds to use for prototyping?  I figure if I come up with any ideas that go past the prototyping stage, then I'll look at looking for specific sounds that work better with a game theme, but for now I just need to find a sound library that would have enough variety that I could use for putting together prototypes.