Last summer I read this really cool idea for how to get frugal souvenirs for a DisneyWorld trip. Link to original article.
If you are traveling to Disney with small children, why not buy Disney themed toys/games/books/animals from places like Dollar Tree, Target, Walmart, thrift stores before you ever go? Then every morning you can surprise them with a gift from Mickey Mouse? They will not need to shop at the souvenir shops and you can save money!