The Book for sure. It was made by the coaches and instructors at The Wakeboard Camp in Florida. It's an awesome series. Very detailed. It's got everything from choosing your equipment, to the more advanced inverts and spins. Definatly worth the money. Check it out http://www.wakeside.com/page/w/PROD/the_book_series_video_dvd
On a budget end, I think detention is well worth the money. Less detail than the book, but it isn't 5 discs long or $80 either. Personally I own both. I like the book for the more detailed breakdown of the tricks.