I do not remember what country you are located in but I have found if you Google these words "jeweler watch supply" you will come up with quite a few companies that sell varying name brands of these watchmaker type knives. It may not get you the exact model you are looking for but there will be many more choices.Here is my watch case knife;
Well, I found a site selling the red Watchmakers by their lonesome, and the blue Watchmaker 10 in a pack. Now to just contact them and ask if they'd sell a blue one by it's lonesome. XD