@DIYandEatCake
I used to have a cake making business, and yes that sounds about right. If you think about it, ingredients for the sponge and buttercream alone would come to about £5 (butter, eggs, caster sugar, icing sugar, vanilla essence, flour, jam) plus another £4-5 if using good quality sugarpaste to decorate (the board is usually iced as well as the cake), plus food colourings. Maybe sugar flowers? Then you have board plus ribbon another £3, box £1-2. About £15 so far? Electricity to cook, overheads like insurance, a proportion of all the equipment you need to buy to run a business like that. So already nearly at £20. Then it takes a good 5 hours to mix, bake and decorate the cake, assuming you want to be paid £10 an hour it’s easy to see how it costs £70.
This is why I do not make cakes commercially. I will make cakes for charity events or friends/family etc but normally the general public do not have a clue as to what goes into making a "proper" cake. The planning of a design, buying ingredients (though I tend to have most in stock), the extras you use (edible glue, ribbons, sugarpaste, colours, nozzles, sprays, flavourings etc) and the equipment come to so much for than "a fiver".
Then you add in your time, lovingly spending hours in a environment that has been inspected by the council etc for cleanliness for less than minimum wage - I can understand why people don't do it for a living. It must be soul destroying. It takes talent, and undoubtedly expensive training courses.
I never understand the attitude when people want something that they could never hope to achieve themselves and want to utilise the best culinary and artistic skills from someone but they are not willing to pay for it. Totally bizarre. Then again, a lot of those people would be happy with a Costco cake.. But to me that is like saying "you don't need to spend £200 on a good pair of quality leather shoes that'll last you years, just go to primark and get a pair for £10" then wonder why they leave their feet reeking of rotten cheese and falling apart within weeks.