Book's costume in Serenity reflects the changes he has undergone since we saw him last in Firefly. He has left the ship and has found a home. Here are his costumes from Serenity.
More after the break...
Some more promo pictures:
A deleted scene pic:
Behind the scenes (he could be wearing the undershirt of his costume...can't be sure):
Pictures from the Propstore Auction:
My Photobucket Album for Book.
Serenifly Costumes site for Book.