Here is an article on the subject.
http://www.freeminds.org/history/launder.htm
Those in the business say it costs about sixteen cents to produce a magazine the size of the Watchtower. If the suggested yearly subscription is about $5 to $10 a year, and only half donate the lower rate, the Watchtower magazine alone would bring in revenue of over 58 million a year.
From the Watchtower media site:
http://www.jw-media.org/people/statistics.htm
The Watchtower, the primary Bible study aid for members of the faith, has an average printing of 25 million, giving it the largest circulation of any religious magazine in the world. It is published in 148 languages. Of these editions, 135 are translated and printed for simultaneous release.
Awake!, published in 86 languages, is a general-interest newsmagazine with a religious slant and has an average printing of 22 million.
Knowledge That Leads to Everlasting Life is the introductory textbook used extensively in the home Bible study program of Jehovah's Witnesses. More than 93 million copies have been printed in 161 languages since the book was released in 1995.