This is just an idea that came to me so don't shoot me if it's deeply flawed.
I'm thinking that since we are a public library and since many people are seeking out popular materials that it might make sense we could boost a record in the search results based on the number of copies we hold.
I'm not even sure it's possible, but how would one go about it if it is?
The reason I came up with the idea is the first result for "Catching Fire" is not the book by Suzanne Collins. Even with a slight boost, it might be.