That was not an E3 faceplate that was the team launch faceplate and was the very first limited edition faceplate they made. Each member of the team was asked to add something to the faceplate, Yes only 500 where made and they where only given out to the people who worked on the 360 and a few others in
PR etc. This is the rarest faceplate out there I think the question about how come they did not make more is pretty simple it was meant as a gift for the team.
I have seen two of them and it is a very nice faceplate but is not really meant for use.
the E3 faceplate was given out last year at the MS press Event. Some say there where only 500 made some say there was 5000 made. The real thing that makes the launch team faceplate so rare is the fact it was packed like any other faceplate that you can buy except it said not for resale. Hope this helps.