It is expensive because of the almonds in it. Generally, the best marzipan to cover cakes is 1 part almonds and 3 parts of sugar. It is flexible and smooth, hence easier to craft in any shape or size. The common price for these types of cakes is about 100 USD for 14 kilos. This is a considerably high cost when we talk about cake decorations. The higher cost individually is the reason why custom cakes are expensive.