They are "cd rom audio cables" that a lot of people who work on computers have laying around. If you have a friend that builds PC's ... ask for a few, or a computer store that repairs stuff.
You can use the older MPC ones that have no locking tab, too. And if you get a several of the proprietary ones (MPC 2 on one end and Sony/Creative/etc on the other), just cut off the proprietary end.