That is soo low! The wedding cake they’ve asked you to make serves 208….so you’re charging a little over a dollar per slice. $250 wouldn’t even cover the cost of ingredients for a fondant covered cake. It sounds like they want a. Particular theme too which takes even more decoration etc. Trust me, I practically gave my cakes away when I started and I regret it now. For me, the bare minimum for the cake should be $3-4 per serving for a basic cake plus extra for details. Work out how much your supplies are going to cost: - cakes (cake mix or flour, sugar, eggs, milk, butter etc) - icing/ganache for crumb coating your cakes (butter, powdered sugar, chocolate, cream etc.) - fondant (and you will need a lot!!) - other supplies, like cake boards, dowels etc. - extra decorations for the cake -water, electricity etc - your time!!
Work out all of those things and then see what you think is a fair price from there. Like some of the other posters said, call around and see what other cake decorators/bakeries are charging for similar cakes. That will tie you a base point.
Hope that helps and good luck!!! That will be a very time intensive cake, so please don’t short change yourself!!