I regularly make cakes for friends and family and charge around £35 for them, so I agree with Panda on that front.
However, I have no doubt that the cakes they are supplying are not nearly as nice as a personalized one from me or Panda!
About this 'worlds worst baker' I bet you're not! Imho, a child will remember a homemade cake by mummy, far longer than a shop bought one. Go on! Give it a go!