There is one material I had thought about that is relatively cheap... I just have no idea if it would be better, worse or no change at all. Aluminium Checker Plate, it comes polished, is readily available and you can get it pretty thin. I thought *maybe* the checkers would be something like a hammertone finish only better because they are polished. But they could also just scatter the light. I've never seen someone use it so if you want to be a guinea pig...
Chris