We never tried to trade pins on board, but we did buy a few on our Halloween 2003 cruise. The gift shops had some (on
Castaway Cay as well) but they did offer limited edition pins at special "pin selling" times in the lobby. Each person was able to buy 2 of each LE pin. The night that I went (from reading it in the Navigator) I was able to buy the special Halloween pins (was disappointed that they didn't both say
DCL -- but too cute to pass up) and I also bought the Opening Day Brother Bear pins since my DS and I went to the premier midnight showing onboard the day it opened.