Ok, so I decided to go the frugal way and get a stone slab from Home Depot. I went in store and there's like a jillion different kinds, and they're broken down to stone from the quarry, ceramic, and porcelain. Stone is unglazed, but I don't think they're the right kind for oven baking. The guy at Home Depot told me the ceramic and porcelain don't react to heat but they're glazed, and I read online that glazed tiles have lead in them, and you don't want that in your body. The last option is slate, which looks really dirty and fragile compared to the other three, I don't think it'd be good for the oven either.
So question is, can any one help me hone down a specific type that I can use? I'd need to know the exact name, and if it helps, pictures. Thanks!
Web:
Flooring - Tile & Stone at The Home Depot