Why do birthday cakes cost so much?

I know people are able to make their own cakes, they are even able to go to Hy-Vee / Target and get a cake for $20 or less.  So spending $80-100 on a birthday cake seems outrageous.  "Why would she charge that much for a cake?" 
Well I want to give you my why!
I charge brides not for butter cream or fondant (since I charge the same price) but for my time.  I spend countless hours baking and decorating their costume cake.    Something they can't or don't want to do on their big day! (And rightly so it is a major project they shouldn't need to worry about on a day of such importance!) 
Birthdays are basically the same thing.  It is a day when mom is very busy making sure all the other details are perfect.  I still spend at least the same amount of time making birthday cakes as I would a wedding cake and now that I make my own toppers I would say I spend even more time.  The Mario Brothers toppers I made I spend 4-5 days in 4 hours sessions to make it all.  Nemo has been about the same and I'm not even done yet.  (I will post a few photos of some more toppers and show you what I am talking about.) My cakes are not something you can run to the store an hour before your party and pick out of the case.  They are carefully executed and thought out cakes custom made for your event! 
Are my cakes a necessity when the economy is bad? No.  Is my cake worth the money though?  I would like to say yes- every penny! Do I have hurt feelings if you email me about a cake and then decide my cake isn't in your budget?  NO!!!  I know my kids wouldn't get cakes like this if I wasn't the one making them!