Peter Pan Costume

You may also try to make the costume yourself (but buy a Peter Pan hat).  Find dark green sweat pants and a green T-shirt (much larger than you would wear, so that it is long).  Cut the neckband out and make a vertical cut near the throat area (to open a collar).  Cut the bottom irregularly as well as the sleeves.  Get a large belt with a holster for a sword.  Some moccasins (or other brownish boots) and you are done...
Be sure to carry a small pouch of pixie dust...
 
Find Captain Hook Costumes
 
Tinkerbell Costumes
 
Think about having a coordinated family costume with Dad as Captain Hook, Mom as Wendy, son as Peter Pan and daughter as Tinkerbell.  How fun!