It’s very hard to tell you if that is a fair price without knowing all the details as to size, flavors etc. Also keep in mind that people on here are from all over the world so what may be a fair price for them may not be a fair price for you. I would sit down and figure out exactly how much it will cost you in ingredients, supplies (boards, dowels, utilities, etc) and how much time it will take you to shop for materials, bake, decorate & clean up. To be honest, I can’t see $35 being enough unless this is a very simple & small cake. I don’t sell my cakes but I know what it costs me to make them.