These can be rotated between the learners. They MUST be at or slightly below the students' current reading levels. You will need variety of topics and variety of reading levels. Don't assume that because the class is labeled Intermediate, that they will all be Intermediate readers. Ask for other published support materials such as worksheets, vocabulary lists, games and extensions based on the series etc.
Most publishers have a wealth of support material at hand only to give away.
Getting funding In the initial stages you will need a large amount to get enough books to start off. Bulk-buying is cheaper. Some teachers ask each student to buy one book they like and then share them. Some teachers use their research budget if they are lucky enough to have one. You will need a constant source of funds for replacing lost and damaged books, updating and improving the stock and so on.