Baking stones!

A good and relatively CHEAP method of obtaining a baking
stone is to go to a local
CERAMIC SHOP. Purchase a NEW KILN SHELF.

I emphasize NEW. You don't want a used shelf, using a shelf
which has been used in firing pottery can
absorb various and sundry items , in gaseous forms, from the
glazes used on the pottery. These chemicals can be outgassed
to the food if they are present.

Again, NEW SHELVES ONLY.

That is what I use and I have had very good results, as good
as the expensive baking stones which are available at the
locas kitchen supply stored in Cincinnati.