2003 might have been the real last ST11s, and police models at that. Confusion arises from when they were produced vs when they are first registered.
As for colours, hard to be definitive. I have not come across information that gives all the colours for outside the US market. The blue is not at all common, and as it came out in the year the gold limited editions ones were sold it may be just as rare. In the US they just mention red.
BTW, I just realised I have a PDF of the brochure that details all the limited edition 50th anniversary colours for various Honda models. The Gold ST11 is the first one listed.