Hi, Jessica welcome back to the Disney Parks Moms Panel!
Exact costs can vary from restaurant to restaurant. Most Walt Disney World restaurant Menus can be found online. I find this to be an extremely helpful planning tool. Seeing what is offered in advance not only helps me budget, I can also see what the best places are for my family to eat basted on their food preferences. Simply select the restaurant you are interested in, and then choose 'view menu' on the restaurant's page. Keep in mind pricing and menu options are subject to change, but this can give you a great idea of how much you will need to save.
Another budget friendly option you may want to look into if you are staying at a Walt Disney World Resort hotel is the Disney Dining Plan. For one flat cost you are entitled to a specific amount of snacks, Table-Service credits and / or Counter-Service credits. There are different plans to meet your family's needs and budget. You do not have to worry about depleting your food budget, and you also do not have to worry about selecting the most inexpensive menu items. For one flat cost, you can dine without stress. Now that is what I call a vacation!
Yet another option is to have a grocery delivery service deliver some items to your hotel room. My family uses gardengrocer.com to order bottled water, snacks, breakfast items, milk, and fresh fruit. We normally eat breakfast in our rooms before we head out for the day and then eat lunch and dinner in the Parks using our Disney Dining Plan credits.
Wishing you and your family a magical vacation, Jessica!
~Rachel