The official T-shirt and memorabilia provider for the San Fermin feast is Kukuxumusu ("Flea kiss" in Basque, almost unpronunciable in Spanish). Their Website (in English) with online shop is
here . Mayebe you can contact them and ask if they have any remain of the 2003 collection.
Their designs are really good and fun and maybe you will bite with something else, even if you don't find what you are looking for.