You can buy a plate of steel that can be used as a "baking stone" which will hold in and transfer heat to the pizza exceptionally well.
If you go down to your local metal supply store you can have them cut one of these plates for you that is thicker (thicker is better) and cheaper than you can buy at any cooking store.
I went this route. There's still a bit of work to do to remove the mill scale and then season it, but it's nice to get something custom that fits your oven.
If you go down to your local metal supply store you can have them cut one of these plates for you that is thicker (thicker is better) and cheaper than you can buy at any cooking store.