Hi Crystal,I don’t sell my toppers sans the cake for now but I am thinking that if I do, I would probably charge it this way; start with what I would charge for a cake with the same topper. From there, take out an x amount for what I would charge for just the cake. For me, the costlier part of my price goes to the customised design, not the cost cake itself (ingredients and such) so the x amount will not be substantial.
Hope it helps.
-- Bito, Handmade with Love..just for you!, www.bunsintheoven.my