While Disney World is crowded during the holiday time, it is extremely fun and a great experience for children. I would suggest staying at a hotel outside Disney World, and possibly renting a car (although most hotels outside Disney World have a shuttle that can take you, but they have scheduled times that they travel at). Also, another way to save on a trip like this is to pack your own food to eat inside the park (I know they tell you that you cannot bring food in, but if you pack it carefully under something in your backpack, they most likely won't see it). You can check out cheaptickets.com as they sell by far the least expensive tickets to any destination.

Happy holidays!