As I've posted elsewhere, I've been retired for eight years, although occasionally, for a special occasion or friend, I will go back into the kitchen. Several months ago, I was approached by a close friend/clergyman and asked if I would cater a buffet luncheon for a young couple whom he was marrying. Both are college students and the wedding was without parents' financial help. Several individuals in the community were providing the means to purchase supplies and volunteering to assist in set-up and service. My capacity was as a volunteer, as well.
As we reviewed the menu, my friend the "preacher" asked if I'd make a wedding cake. I explained that I would be happy to bake the layers, lay down the scrub/base coat of frosting, but that my decorating skills were rudimentary. He said, "Don't worry, I'm sure I can find someone with decorating skills." Long story...SHORT. The church has a multi-level faux silver structure that holds four graduated cake layers on glass platters. I baked four rounds using your basic Duncan Hines mixes with added instant pudding mixes, additional eggs, a mixture of two viscosity oils, almond extract and a water/milk/cream blend. I slightly overmixed, so the cake would slice easily and hold its body. I secured several pounds of white butter and made a simple buttercream frosting. (I did cheat a bit with some palm kernel oil, so the frosting would hold up without a stabilizer.) My volunteer cake decorator, as I expected, was imaginary.:crazy: I frosted the cake, piped on some white lacing, added some fresh flowers to the metal standard, and stuck a remnant bride and groom from a previous wedding atop it. I'd estimate that the cake's ingredients cost less than $100.00. It was made on the premises, so there was no transportation cost.
I thought that it looked and tasted very good; simple, tasteful and tastey.
Several guests asked which bakery had made the "delicious" cake. I gave them a ficticious name. I don't like baking these things and had no intention of fielding requests for wedding cakes.
The long and short. In a pinch, you can produce a very acceptable wedding cake for a modest wedding at a very reasonable cost to you and your clients.
If you're talking fondant and custom precision decorating; that's an entirely different arena.