-Forno Bravo has the best online selection (all carry a 10 yr. warranty): http://tinyurl.com/2d7psr3

And of couple of tips for general pizza stone use:

-If you intend to put in on the grill, heat it up with the grill and elevate it from the grate (bricks perhaps). Intensely heating one side of the stone will cause it to crack, I've confirmed that ; )

-Likewise, heat it up with the oven and start with a dry stone. Any sudden increase of heat can cause it to crack, as well as water absorption and steam release (think of bread rising).

I'm with pierino on this one, but also would strongly recommend that you get a large rectangular one, as it will be more versatile than the ubiquitous round ones. Also, you need to be able to remove it easily from the oven without too much difficulty, so keep that in mind. Good ones are heavy. Carefully measure your oven before you go. Also consider buying two, if the dimensions of your oven make that practical. I'm really surprised that the one you bought cracked. I'd take it back to wherever you bought it and ask them for a refund. A baking stone shouldn't break, ever, unless abused somehow. ;o)

I don't want to recommend a specific brand but I would suggest going to a good cookware or restaurant supply store and evaluating them yourself. Key considerations: will it fit in your oven? do you use a peel? If the answer to the second question is "yes", then also make sure that your peel and your stone match up for efficient transfer of dough, as in bread or pizza.

Pampered chef actually has great quality ones. You can buy direct online too. I've had one for five years and have never had an issue with it, and love it.