depends, its a fairly common kind of wire, but it can be in practically anything but in the same sense nothing specific, like its not just in every speaker system, but it could potentially be in any speaker system......they are dirt cheap from china, like £3 for a set of 20 with the matching port
if you are really against buying, best places to look would probably be small speaker/audio systems i would guess, i cant think of anything specific though, you may be able to use FFC cables from a old DVD/CD drive, it all depends on what it is you plan to use it for
