I am not aware of any formal co-ops of this genre, but DE FACTO this already exists for some escorts I know. The guys at some point had ads up, but not anymore. They are working with a handful of regulars with whom they are comfortable. The regulars keep the escort in a certain life style he is accustomed to.
The issue with formal arrangements is that these are not enforceable, because of the nature of the business it is. There are also practical issues. What if 5 guys in the co-op want a Friday evening appointment? I see nothing but problems.