I need some help, I'm getting ready to start school for baking and pastry arts and am new to selling my product. I have baked lots of different cakes, cupcakes,etc.. but when it comes to servings and pricing I am at a loss. A friend's sister sent me this image she would like for her son's birthday.

She wants a cake to feed 20-30 people. From everything I've googled the sizes of each tier seem like they would be so small that the cake wouldn't have the same look. So, help me out here.. what would you suggest on tier sizes and pricing? Would you do a three tier for 20-30 or try to talk her into a two tier? Any advice is greatly appreciated!