From memory there are French, German, Canadian, Scottish and English outfits as well as the 20th anniversary magician's outfit for sale at DLP and maybe a Halloween outfit during the season.
I also saw a pilot, a Buzz Lightyear and a Star Wars Jedi Training Academy costume. Christmas and Halloween costumes were also avilable in some stores in Frontierland.
They should be but other good places for Duffy outfits are the other Disney shop in the Village, Story Book Store in Fantasyland and Thunder Mesa boutique in Frontierland. I don't think you will have any problems finding them.
Ahh, which outfit is he after first? My DS is also a big fan and has er, several, Duffy bears now. His first choice was the pirate outfit and the one that amuses me most is the German one as DS thinks it is a Peter Pan costume .