How much would you be willing to pay for a cake

[emmy1305]

Hi I thought I'd just pop on here to ask around how much people are willing to pay for cakes. I've baked a fair amount of cakes for family and friends and they all say they taste good. I've sold a few cakes to friends but only charged for ingredients and sundries as I didn't have much confidence in my baking. Now I would like to start increasing my prices.
How much would you pay for the following cakes?
8 inch round, 4 layer cake with fresh cream and fresh fruit and maybe even chocolate
8 inch round, 4 layer buttercream cake
These are mostly what I am making at the moment but obviously on request I would make others.
Also I'm living in the south if that helps (about 1.5 hour north of London).
Thank you :)