Basically, an order of an extra topping can easily become an entire new pizza of its own. And it will.
-You've called Speedy Pizza
-Hello, I would like two vegetarian pizzas please, with extras of olives, ham, and pepperoni.
-Okay, that will cost you (???)
-Your pizzas will arrive in 15 minutes.
-Here's you six maximum size pizzas sir, you owe 181 Swiss Francs