It's simple: dirkvl did this as a hobby/experiment/test/whatever you want to call it. dirkvl is either a student, has another job or both, this project isn't dirkvl's company and dirkvl doesn't want to do it again, at least just yet.
dirkvl isn't like Apple - dirkvl makes this in his bedroom, it was a one off thing. Is it clear now?
You can see that somebody is selling it on ebay, go get it there before somebody else does, or be patient for somebody else to produce another keyboard.