Hello bronekkozka, bummer about losing the auction. Be patient. They come up not too infrequently. I got a black Kobalux one about a year ago for 175 British pounds. It was cheap because the ring around the front element was lose. I tightened it myself and it's fine now. I tested it against a 21mm super angulon f/3.4 that I had. I couldn't discern any difference in image quality with both lenses at f/4 to f/11.
The kobalux is clearly sharper in the extreme corners at f/4 compared to 2.8, but in the majority of the field, the difference is extremely slight. I.e., the Kobalux is fully usable wide open in my opinion. Both lenses seemed best arounf f/5.6 to f/8, but honestly, at f/11 the difference was perhaps imaginable, certainly not striking.
The SA was smaller in diameter, but about the same in length. The build quality of the Kobalux is good, but the SA is a Thing Of Wonder. I sold the SA as 21mm isn't a focal length I use very much, and will keep the Kobalux forever!