Both Lowes & Home Depot have unglazed tiles. I have seen it at both stores. That being said, I have been extremely pleased with the performance of the Fibrament stones. They take longer to heat up but they retain the heat better and bake better. It is worth the extra money to have it over the tiles. After years of replacing tiles I gave up. I have 2 15 inch round Fibraments.
PNW