I'd like to buy a marble slab in the Bay Area, preferably the Peninsula. This would be for rolling out pie dough. I know I can go to a kitchen store like Williams-Sonoma or Sur La Table, but I'd like to spend as little as possible. So I thought about going to a flooring or tiling store to see if they have leftover remnants of marble they can sell. But would that be food-safe? Would a marble slab purchased from a kitchenware store be more appropriate - for example, it might be sealed? Any recommendations on where to go? Thanks!