I second that. Avatar: The Last Airbender deals with a lot of potentially serious material deftly, with humor and grace to match. All three season are on Netflix's Instant Streaming.
Welll. I just did some light searching and was unable to find a way to purchase all 3 books at once except via TheHut.com. Hope it's okay to link it:
http://www.thehut.com/dvd/avatar-the-last-airbender-the-comp...
There were tools...
http://news.cnet.com/8301-1023_3-57584518-93/netflix-cuts-ba...