If it's a book, chances are it will end up in your library. Have some policies in place for how to deal with classroom libraries.
Here is a free program that teachers can use to organize their classroom library: Classroom Booksource
Classroom Library policy developed in January 2002 by The Classroom Library Task Force and Educational Staff from AUHSD
A justification for the purchase of classroom libraries.
Here is a sample charge slip form used in AUHSD to submit fines for classroom library books.