You can probably buy one from macsales.com or macresq. You may have to call them. Smalldog may have them too. Or Powerbookguy.
If you find someone who has one, it won't copy. I've tried to copy mine and it was a no-go.
Finally, if the Pismo has had a Firmware Update, the test CD probably won't boot it. I can't remember for sure, but that's how I thought it worked. The original 9.0.4 CDs probably won't boot it either, after the update.