Ok, I'll throw the bovine excrement card....
I agree with N. Ontario Smoker. It's just a piece of stainless bent into an open top box that you put right under the broiler element to get screaming hot. Hell for $10 you could probably make a couple of them. One concern I would have is home ovens are not made to run like that in broiler mode. You could seriously damage the upper part of the oven with prolonged high heat like that.
Could you not accomplish basically the same thing with a ceramic pizza stone or flat pizza steel on the top rack?