A note on snacks.
Some people note that the kids (and the adults too) would rather have Disney food rather than the same snacks that are available at home. And that makes sense.
My thought is to get the snacks that your family really likes but you don't normally buy at home (sugared cereal, chocolate sundae pop tarts, the expensive fruit snacks, chocolate covered oreos (but only if you're going in the winter cause otherwise they'll melt), etc.
Yeah, they're not as healthy as some of your regular snacks might be, but they are probably better for the family than Disney snacks (most fruit snacks have 100% of daily vitamin C. Of course, they also have that much sugar too, but it's vacation, relax.

) But, even the more expensive snacks in the grocery store are less expensive than Disney snacks. And, if you're trying to save money, the family is more likely to settle for the "good snacks" over Disney snacks than they are to settle for "the same old boring snacks from home".
For my family's trip to Disney at Thanksgiving, I've already got some dinosaur eggs oatmeal for breakfast, cookies and creme granola bars and chocolate sundae pop tarts set aside (and this is all for me. I'm the big kid on the trip.). I'll add Combos and maybe some home made chocolate chip cookies and/or rice krispie treats to that as well as some small size chocolate bars (although I might make a deal with Mom and Dad that they bring the chocolate and I'll bake the cookies. Have to see.)