Honestly, the Apple kit is a rip-off. US$50 for a bunch of adapters is a joke. OK, so they fit perfectly with Apple's power bricks, but that's just too much money.
Provided that the power brick (yes, that's the technical term 😉) is a 50-60Hz, 100-240V transformer, then all you need are the appropriate prong adapters. Go to a Radio Shack (or the Aussie equivalent) and buy the proper adapters (about US$3 each) for the countries you'd be visiting.
Or you could pay more for the Apple kit and have a matching set. Nothing wrong with paying more to have matching stuff, but if you don't care, go for the cheaper stuff.
ft