Had to chime in here. (Long time lurker, et al). I worked at Publix Grocery in Charleston SC as a decorator apprentice. I was able to visit all the Publix stores in the greater Charleston Area (about 14, if I remember correctly). We decorated the decadent cakes in house with pre-made cakes, frosting and fillings. The variation in how they look results from skill level. Lots of times the Decorator Apprentice is the one making these to "train" so they can make birthday cakes (typically the biggest seller in the bakery - as in on the weekend we'd have 60-70 cake orders a day, divide that by 3 decorators).
After watching and filling that case for 5 months, I can say there is a market - but 80% of the cake sales were only on the weekend. People go to church and want something special for dessert that evening, so they stop. During the week, we'd mostly sell the cupcakes, truffles (pre-made, and decorated in house), and chocolate dipped strawberries (hand dipped strawberries from the produce department, dipped in house-made ganache). For some reason they didn't sell well on the weekends.
I think there is a market for these, but really watch the sales. Otherwise you'll have a bunch of cakes going bad during the week and an inability to keep them on the shelves during the weekend. Also, you'll want to market to church groups, other groups that meet on Sunday. You might even want to do a door-to-door campaign to get the local residents to but them.
Just a few thoughts.... OK, I'll go back to lurking now!~ ;-)