I discovered this when answering a recent fan's email.

I'm not sure when it disappeared from Sony's site. It used to be that Sony linked directly to the Amazon page, which is how I ordered my official set. Now Amazon lists it as an audio CD (!) starting at the low low low price of $70.32.

According to this site the official release date was Tue, April 3, 2012. (Curiously, Amazon has listed the release date as Sun, April 15, 2012 and Mon, April 16, 2012.)

Places online which seem to have it still in stock that I will be passing on to the fan who recently contacted us: