I did a candy buffet at my at home wedding (not at Disney) and it was great. If you're having your wedding at Disney I know they can be strict with the rules for this and what you can bring in yourself. I think I remember people saying they had to go through Disney to do it and it was going to be really expensive.
My parents gave me some grief beforehand because they thought most people wouldn't want candy or would be too full. Well, this turned out to be a huge hit at our wedding! Not only did it look really cool, but people were lined up to get some candy! Everyone enjoyed it - kids, adults, grandparents.
We decided to do candies that matched our colors, so all of our candy was blue and silver. Some things, like Hershey's kisses and York peppermint patties, we were able to get in Target and places like that. Others we ordered from a website - we used
http://www.acandystore.com. I think we had 8 different kinds of candy and I got 5 pounds of each. The majority of it was gone by the end of the night, though some candies were more popular than others. We still have blue taffy in our living room candy bowl
We also got the jars and stuff from various places for pretty cheap, like Target, Walmart, and TJ Maxx.
It might not work if you are having a small wedding, but anything medium sized to large I think it would be a great idea. We had about 80 people. Here are some pics: