All cakes can be stuffed with baby products in the middle. I base the prices on how much went into the cake as of supply and my time in making it. 

*One tier cake= $75

*Two tier cake= $100

*Three tier cake= $125

*Four tier cake= $150

*Five tier cake= $175

*Diaper baby= $25

*Custom diaper= $125-$175

-Bike

-Stroller

-Carriage

-Diaper box

Here are my diaper cakes that I have done in the past. My little portfolio and growing. See if you can get some ideas that I can do or try for you.