They have a fair sized scrapbooking section at Mouse Gears in EPCOT. Also most of the resort gift shops have small scrapbooking sections. I've had good luck at the store in Downtown Disney!
Also at EPCOT world showcase the CMs will be happy to give you the doo dads that they affix to the kids masks for scrapbooking. I found this out when I was talking to a CM at American Adventure while my kids were making masks. She asked if I scrapbooked and when I said yes she gave me a rocking horse cutout and told me many adults collect the cutouts form the different countries for scrapbooking or to use as stencils!