I'm not sure whether you're asking about the site, seobook.com or the book, The SEO Book. Either way, my answer is the same. If you are serious about SEO, both are definitely worth the investment.Originally Posted by hendricius
Membership to seobook.com is currently $150/month. The site is updated regularly and includes a wealth of knowledge on both SEO basics and the latest and greatest trends. I believe the book is still included with the membership. Aaron has also posted some videos and software utilities that will aid you in your personal quest for web domination.
The book ($79) isn't updated as frequently, but has hundreds of pages of information that is still extremely useful to SEO's, regardless of the fact that the industry is always in flux. It's definitely a good investment, especially for people just starting out. The book is usually only available in PDF.