Registration of articles : A Focus.

I have always collected Registration labels, I used to buy a glassine full for $2, at a time when men wore ties.

This is currently $25 on ebay, and climbing,  my sad little offer of $2 is long gone.
Cannot see anything that stands out, perhaps Rabaul?  Turks Island?

I would think Ascension to reasonably common, the Bangalore though,  good suggestion.
Indian collectors abound, and they are an unusual bunch, like the collectors of Ajman etc.
I could see them paying for that.                 >$25 is still a surprise for me, for that page.