I have a very wide forefoot (no bunions though) and I'm fine in Specialized Torch shoes.

But I ride outdoors exclusively. My soles are nylon, so they're not super stiff. But I'm with alpinerabbit, I don't know why you'd need extra stiff shoes for indoors. I think most people, if they have a dedicated pair of spinning shoes, probably spend less on those than they do on their outdoor shoes, and wouldn't spring for carbon. But what do I know.