Hi Diane, Welcome to the Disney Parks Moms Panel!
Oh gosh, this is so exciting that your granddaughter is going to Walt Disney World Resort with her high school band! She and her friends are going to have the best time and make some amazing memories that will last a lifetime. And you are such a wonderful and thoughtful grandmother for wanting to give her such a great gift!
It sounds like your best option would be a
Disney Gift Card, which can be used at almost every shop, restaurant, snack cart, and more, at all Walt Disney World Resort theme parks, water parks, and even Disney Spring. For Christmas my own sweet grandmother gave my family gift cards for our upcoming trip and I'm already deciding how I'm going to treat myself while there.
Disney Gift Cards in smaller increments can be found at major retailers near you, including grocery stores, big box stores, drugstores, and even some warehouse club stores. However, you can purchase larger denominations online where you can choose from
hundreds of great designs. You can also choose to send the gift card
electronically to your granddaughter's email address, which might make for a fun day-of-arrival-surprise.
Pro tip: be sure to save your original purchase receipt and have your granddaughter take a picture of the back of the card. This way if it's lost or stolen, there will be a way to track it's remaining balance and issue a new card.
I hope this helped, Diane, and I hope your granddaughter and the entire band has a blast!
~Kristen