How does a zen garden relate to zen?
If you are doing market research to emulate a rock garden I can recommend this book. It centers around a fellow who are making these gardens based on his understanding of zen, accompanied with maps, pictures and explanations on how the aesthetics were formed. He also makes gardens from either a traditional or modern approach. Certainly you will be more interested in a traditional style if I caught your drift, but you might be interested to see how it translates into a contemporary environment.