I'm taking their full-length course right now and the instructor said it's not necessary to buy the LRB with our course materials. Though, the book is made avail online and I felt reading it was a lot of help. I think some ppl say you get access to the book too if you take their weekend course, so may be it wasn't necessary for you to buy the book, but may be you wanted the hard copy. Other then that, they advice you not to do too much b4 taking their course becuz you tend to pick up bad habits from practicing on your own.