I can vouch for that jules, we stood next to them with our Trade Stand at East of England last year. Have to say business certainly was not brisk! Problem is the 'pet' people want stuff cheap, and the 'show' people tend to stick to what they always feed.
Specialist stuff like this is not a very good commercial proposition. I would stick to making it for friends and family. Also if selling it commercially I imagine you would have to have council approved facilities for the baking and packing etc.