We have found that there isn't much at the parks anymore as far as buying goes. Most of the Disney stuff that I do buy comes from local Scrapbooking stores and Michaels. They do have 12x12 albums usually (my mom got a really nice one last year or the year before).
While on my trips I save a bunch of things for scrapbooking purposes. Napkins, bracelets from parties, KTTW cards, receipts, park maps, hours, activities cards from the resort, stuff like that.
I do also take quite a few pictures with scrapbooking in mind. But I also love to take pictures, so I always have way more than I probably need.