Well, it would appear that today is a lucky day. Havoc has been released for free in a binary form to any who request it, with a few limitations of course. But if your game is $10 or less it's 100% free, including if your game is free or private (personal). I think they may let indie folks off with a small fee, or even free if it's your first game. (Just a suspicion though.)

For more information see: Havok General Information

To request your binary library: http://tryhavok.intel.com/