The search was a long one for several reasons, and I think many of these reasons are applicable to searches in general. Below is a partial list of challenges I faced searching for these rare birds:
The primary challenges were not demand issues, in this case, but rather supply-side constraints. Specifically, the supply pressures included:
--low production numbers (the watch was only produced for a single calendar year in '64);
--specific geographic concentration (the majority of these watches are tucked away in private Japanese collections);
--particularly strong sentimental value resulted in low secondary market participation (the World Time were an Olympics commemorative piece, marking Japan's reemergence onto the world stage after WWII, and many people place particularly strong emotive value in them);
--speculative pressure (the Olympics will come to Japan again in 2020, and so the value of these watches is expected to increase significantly in the future, making the current market for them very tight);
--information shortage (most of the information about these watches are in Japanese, and this can make sourcing the correct piece that meets informed expectations difficult);
--culture / time (Japanese often repair, update, or otherwise modify their watches over time, replacing crowns, dials, and so on. This creates a further supply shortage of purely original pieces).
After staying with the search for about a year, I finally located both models within the same 24 hour period, which is kind of shocking really. Both were in private collections, one was located in Japan, the other in London. Negotiations were smooth and within days I had completed my search - just in time for my dad's 65th bday!
Keep the search alive, and enjoy the ride,
Cheers,
Matt