I stumbled on this similar example. The Good Beer Guide lists the best pubs in Great Britten that serve "Real Ale" (cask beer). This Camra guide was responsible for reviving traditional British beer, and lead to the start of the USA microbrew revolution a quarter century ago.
Prices:
Members: $ 16 +P&H
NonMembers: $ 21 +P&H
iPhone App: $8
Obviously, there are more production costs for their iPhone app than just a pdf file. Camra has more volunteers and much more content in their guide. They also have more institutional and marketing expenses that need to be supported from sales of this guide. They also have much higher sale to bring down the printing costs.
Rambler