Here is my tip for a family on a tight budget. There are enticing things for sale everywhere you turn in Disney World. Money can flow like water if you're not careful. Here's what we do on each trip...
If our girls see something they want, we take a picture of it on Daddy's cell phone. On the last visit to that particular park, we look through the pictures at the end of the day and decide what item they want the most. It works tremendously well, and at the end of our trip, we've stuck to the budget to the penny, never use the credit card, and have the absolute time of our lives! Both girls get a few toys and trinkets that they still love and play with.
This also works well to cut down on the whining and begging. Our girls have been firmly trained that this is the rule, and no whining or begging will change the rule. They now see something they want and immediately say, "Daddy take a picture of that for me!"
A co-worker of mine went to Disney last year and called me from his cell to answer a work question. He was lamenting that his kids began whining and crying for stuff immediately upon entry into the park. I gave him my little tip, and it worked great.