They sell it as an attachment, may be able to add it to other grinders. The first plate is very big because there isn't a blade before it so the meat has to be able to be pushed through the holes to hit the blade. Looks like it is a very coarse grind on the first, probably just enough to be able to run it through the final plate.
Amazon has them for $150, not having to grind twice would be great as others have stated the second grind can often be a PIA.