Get on line and find a local bulk food distributer and tell them you are making pizza's for a charity event and if they will sell to you, all you need are the basic ingredients: (frozen shells, pizza sauce by the gallon) (thinking about 4-5 gallons)(pre-shredded Pizza cheese, by the bag) (pre-cut pepperoni sclices)(italian herbs & spices)If you are going to take on the task of baking these as well, depending on what type of oven you have, you might want to invest in a baking stone, if you need more than a few, and it starts to get pricy, you might consider going to a fire place brick vender and purchase some smooth faced internal fireplace bricks these will bake your pizzas faster and will hold the heat in the oven during the constant open and closing of the oven door. The food supplyer usually sells cooking ware as well. Don't forget the pizza paddle and lightly sprinkle yellow cornmeal down on the baking stone to keep the shell from sticking, and makes for easy pizza removal. you will need to add and remove cornmeal as you go to keep from burning the used cornmeal.(hint) if you need 300, better be prepared to screw up a few and for testing, heat, ingredient amounts. Good luck!!