I just wanted to let you guys in on a little secret.  I have been at MTSU for five years (but i'm done in 6 days) and I just now found this out. 

When you are attempting to sell your books back do this little thing that could get you $5 extra per book.  Take the yellow "Used Textbook" sticker off anywhere it is located.

When returning my books the other day, the clerk gave me $31 for the same book that my friend recieved $36 for.  So I asked him why, he said, "His was probably new, yours has this used sticker on it, so we give $5 less than we would a new one." 

So this means that if you remove the sticker, they would think it was a book that you bought new.  Just thought I would pass it on. 
Doesn't hurt to try. 
If you make some extra money, take me to lunch!