Forum is free, it's required registration only. Hovewer Membership and Blackhat zone + ebook comes only with payment. (sidebar)
Full access to forums and ebook, including source code is possible for free without spending any cent.
Hovewer you need to :
You need to have 1000 posts in open categories (soon more categories)
Write 25 high quality articles about android development, Google Play, etc. (limited time)
Publish your source codes in closed forums (send me list via PM)