The original G*S*G printed circuit boards have all sold. Shannon has not yet committed to making any more to sell. (That may change).
If you go to the "DIY HIFI" Board (on this, diytube forum), there are still THREE (March-03-2021) more PCB boards for sale to build a (Octal Base Tube) DHT-SET amplifier.
I made the boards because I needed more G*S*G boards. When I sell the last three, I will not be making any more.