I found my quarry tiles at Home Depot, and they 6 inches square and slightly under 1/2 inch thick. Six tiles weigh 7 pound, 13 ounces, and they made a 12x18 inch landing zone for pizza and bread. Not the ideal size, but I couldn't beat the price - I paid just 67 cents a piece for the tiles. I bought 12 since they were so cheap.
One criticism of quarry tiles is that since they're made for floors, they may not be food safe. Lead is the usual culprit that people worry about, so if it's a concern, you can buy a lead testing kit and see if your particular tiles have a higher lead content than you're comfortable with.
As with the previous test baking test, I preheated the stone for an hour at 550 degrees. I tested the tile temperature at 45 minutes, and it was 553 degrees. At 1 hour, it was 554 degrees.
The pizza baked for exactly 8 minutes and emerged fully cooked and crispy.
The bottom was nicely browned as well. I thought this pizza was better than the one baked on the cheap pizza stone - it was just a little crisper on the bottom.
One downside to using tiles is that you've got a lot of pieces to put in and take out. A stone is just one piece - well, maybe two if you're using one that has cracked. But arranging six tiles so they're in the center of the rack and butted up against each other takes a little more time. In theory, you could leave them in the oven, but I'm constantly moving my oven racks into different positions. Even if I take the rack out with the tiles on the rack, they move around enough that I have to readjust them when I want to bake on the tiles.
Also, if you're a little rough with placing bread or pizza, those stones can shift around as you place your baked goods on the tiles. Sometimes that makes a difference, sometimes it doesn't.
Another downside is that whatever spills onto the stones can drip between. Whether that's pizza goo or cornmeal, it can end up on the oven floor.. A solid stone will contain that mess much better.
The last downside is the size. A 12x18 inch landing zone is pretty good for baking bread, but it's just a little small for pizza.
As far as I'm concerned, tiles are a great short-term option while you're waiting for a better stone to arrive. For long-term use, they're a little annoying to work with.