Not sure, I (luckily) got mine after registering my kettles last summer and calling Weber CS on a broken plastic Performer table, they shipped one out for free.
The upgrade to the metal tables over the plastic is easily my favorite upgrade. Love my brick red Gen 3 with the metal table upgrade, on the hunt for a Crate and Barrel Green or Blue Performer to put a metal table on. Looking forward to hearing if Weber will sell them, I kinda just assumed they would.