Many recommend looking at what professor has listed for books (if they have it on some communication before class starts - and doing some preliminary looking at costs and sources) but going to first class and seeing syllabus and hearing what professor says before making any book or other supply purchases. Many times my students (at UA and UAB) found some books could use an earlier version, etc. Much cost savings by waiting. DDs also found many sources for books - but key is ISBN number, any codes that are purchased with the book (for electronic access for stuff critical for the class) etc.