It's been said before, but when it comes to keycaps and accessories, you should buy when you have the opportunity. Not for what you currently have, but what you might want in the future. Better to have something you don't really need right now, than need something you can't get later.
For instance, you might think you'll never have or even want a Korean custom keyboard, so you have no need of a tsangan compatibility kit with your keyset purchase. Then later, when you finally obtain one of them, you regret not having the correct keys for the bottom row.