Sam's ClubDaily Chef makes a decent carrot cake for $18. I didn't love the frosting but the cake itself was pretty good. If you are pressed for time this Thanksgiving, you could buy it and doctor it up. Use a spatula to clear the top layer of frosting and make your own sweet potato cream cheese frosting.
BTW, I took a photo of the cake using the Canon Rebel SL1. I am loving the touch shuttle function of the camera.