I’m sure they are lots of cake pricing guides online,but When I baked for a Country Market co-operative,we were always advised to triple the cost of all our ingredients,etc,to give a base selling price and this works quite well for me as then some of your labour is taken into account too. Cutting cakes are usually sheet cakes as kakeladi said,simply decorated to ensure enough servings for all the guests.There are plenty of portion guides online for different sizes/shapes of cake. I hope this helps you work it out.good luck.x