However, half price is offered only during the week of final exams at the end of each term in May and December. While not all titles have a resale value, students may receive HALF the new price if the title is being used again the next semester and is needed for inventory. Your instructor readopted the book for the next term. We already have a gazillion of 'em in our bookstore, so we can't use it here. It isn't needed here, but it is needed on other campuses.
Demand determines the value.
The new edition is in, so the old edition is out. Your book looks like it's been through a tornado.