have many folk here read Terry Pratchet's disc world series?
I'm put in mind of the Thieves' Guild of Ankh-Morpock. They replaced the City Watch as the law enforcement. Everyone was still vulnerable to some form of theft or extortion, but they issued receipts and the like, which made sure the thefts were evenly spread.
I'm no thief, but it might be more amusing if the master thives were to adopt some form of trademark, so you could tell when you have been done by a true profesional.
Just an idea, I would not wish to tell Insh how to run the guild, she seems to be doing a good job anyway.