Jonathan,
Don't listen to these people!
Don't raise your prices.
Lower them.
Actually, I have a copy of the 12 manual and like it very much. I especially enjoy the little videos, with Jonathan's narration, which are very entertaining.
At this time I'm not employed using VW (for which the industry can be very thankful), so I don't need the books for my job, but I like to read anything on the subject.