The disney autograph books you can buy at the park def. get the job done. And you can alway pull out or scan those autographs to add them to scrapbooks/ mini albums later. Making your own is so personal and gives it a little extra touch. Which with the digital age its also super easy to do just this.
Now you can make all your cards ahead of time and have the characters sign them for you to then use the cards later. ( Sizing on this is important because with the characters in their authentic attire it can be hard for them to sign the card. I would suggest to make it a 4x6 size minimum... while bigger is easier for some characters, they are used to having around that size to sign on. So keep that extra big pen handy for them.)
Are you a digital scrapbooker? If so check out Capturing Magic. It is a disney scrapbooking oriented site, that focuses on digital scrapbooking. Not only do they have some awesome images, you can get some free autograph cards by signing up as a follower to their site. Also the link I attached shows you how to have the characters sign your phone so you can take the image and insert it to your cards for scrapbooking!
Below are some cards that other disney fanatics have made and shared on disney forums for others to use on their trips. If you search around on photobucket you can find the makers of some of these cards, since thats where most of them have posted the cards at.
Keep an eye out for more of these autograph cards! This is just a few that I have found and grabbed.