I've always wondered if they are gonna make an entire series DVD including all three chapters, but the show ended over a half a year now, Nick's probably forgotten all about this show now and are now concentrating on "Other (SB/KCA) Shows." But really Avatar having a complete box set with all the charaters, episodes, and chapters would be a very good idea in my book. Who knows maybe they'll do it when that Live-action movie is released into theaters.
So yeah right now just try and get each of the DVD sets with different chapters and volumes in each one. Hopefully they don't cost too much money now. Good luck getting them all.