The cost of a 12-inch round cake can vary greatly depending on several factors such as the bakery you choose, the complexity of the design, the type of ingredients used, and the location. On average, a simple 12-inch round cake can cost anywhere from $40 to $100. However, a custom-designed or gourmet cake from a high-end bakery can cost significantly more, potentially ranging from $100 to $200 or more. Remember, it's always important to discuss your budget and specific requirements with the bakery to get an accurate quote.