The 10th book is available with Real Studio Developer Magazines.
Normally the year books sell for $49, but with pre ordering you get 25% discount, so it's $37.50. Order here.
Or you get your copy for normal price in Orlando on the Real World conference.
Anyway, the magazine is great as it is more up to date than any book available and an huge library of Real Studio knowledge. I recommend everyone to have a copy of the back issues to browse.