Originally Posted by Allzright
Unglazed tiles at Home Depot are a regional item.
I think he might be right. On the West coast it seems like it's a normal in-store item, but going through Louisiana I tried to replace one of mine that cracked and they didn't seem to know what I was talking about. I prefer the full coverage with tiles and they fit like a glove in my particular oven with just about the perfect gap all the way around.
The down side is when they crack, they have a tendency to slip down through the oven rack and can scratch.