I ordered the ring and plate from Weber yesterday afternoon.
Diffuser plate, Master-Touch 67571
Charcoal chamber, black 67587
I've wanted that diffuser plate ever since this model was announced but always read they won't sell them. Figured I'd give it a shot yesterday and lucked out. I've looked around and have not come across a diffuser plate that is as well made as the Weber version.
If you decide to call it in, ask for a discount. They are able to provide one when asked.
Weber is discontinuing that model of Master Touch in the US. The lid doesn't seal properly. Hence the Costco liquidation.