Here is a brief summary of how we set up our reading groups In North Lincolnshire:

•  we buy multiples of 10 paperbacks per title
• we store them away from the library shelves
• we buy mainly in response to what the reading groups ask for
• we reserve the right not to buy (eg if they want 10 copies of a new hardback non-fiction, we would consider that not suitable for use after the reading groups)
• when we have bought something in response to a request from a group, we circulate details to all the other groups so that they can have a chance to borrow it as well.  We maintain an up to date list of everything in the collection
• after the books have been in stock for around 18 months and been used by all who want them, we disperse them into standard library stock
• we advertise this service as an incentive to people who are setting up readers groups which will run independently of the library service