I don't want wood supports, I would like metal--something sort of contemporary and simple. Where can I find something like this?
Van Dykes sells a variety of decorative metal corbels, as does Restoration Hardware.
Here is a link that might be useful: Van Dykes
The best I've seen are at Shortrunpro.com. They've got a lot of selections and I think you can customize them for your exact requirements. Some are extremely heavy duty, even 1/2' thick steel.
Here is a link that might be useful: Shortrunpro
Try OUTWATER PLASTICS! They have the most amazing array of items, trims, knobs, hardware. They have a good website. I believe they have some metal brackets like you want.