We got the storm trooper helmet at Engineears in DCA last month - but they were almost out of Darth Vadar helmets- we dug and dug and got the last one!
Good tip about the arms - we found we only got one arm that really "holds" all the Disney extras, so try them out before you make your final decision.
My 2 sons were set on getting classic Dis headgear (ears, Sorcerer's Apprentice hat etc) plus Buzz, Storm trooper and Vadar accessories, so Mr PH had to miss out on some really cool big items, like Ariel hair, Dumbo ears and I think Tink wings?
Choose your theme, collect all your bits and then sit down on the floor like DH and work out how the heck to fit them all in the box with the lid still closing! We were there for ages, but it was a great souvenir ( $18.95) Our two Mr PH bodies that we had already at home now look very smart !