You mean the black one with the scion logo right?
Try watching E-Bay. I know I’ve seen ‘em there before. Just did a quick search and I only came up with the JDM ones (white with Japanese characters and xB on it.) Also, you may want to check with the local dealer, he might have one lying around.
I've seen lots of different plates. You mght try posting a 'pic of the one you're after.