I ordered a refurbished one. And surprisingly they had one in stock. Now it's on the way. (It's Amazon Marketplace, as you suspected.)
I wanted to save money for a used Cintiq Companion or a smaller MobileStudio Pro, but I couldn't wait. Since my main drawing tool is Clip Studio Paint, I thought that it might work well with Galaxy Book 12. (I also use Sketchbook Pro 7 occasionally. I keep using the serial number I bought from Amazon.)
There are some tests and demos with Galaxy Book on Youtube, but there are not enough reviews and demos with drawing on the tablet PC. I can live with the fan noise. And I can live with the shorter-than-advertised battery life. What I want to know is how S Pen works with the drawing and painting software.