As you already know, Panerais are always hard to come by especially @ a Boutique or AD.
In my case, I was really lucky to have found the 249 @ an AD in Tokyo before the JPY hit the roof.
Now to answer your question
hmmmm........
I would have to say it took me the longest time to obtain pam 123 as I it was my first panerai
and traveled over 4 countries to find it when in fact it was innocently laying on the display @
a Panerai AD right here in Seoul Korea(this was when Panerai had an AD in Seoul)
and what an eye you have !!
1A, 27B, 29A, 87G, 123, 127, 140, 172, 217, 249
thanks
Cheer~!!