World Coin Rarities?

Yeah, US "rarities" are often dead common in terms of numbers available in the market, compared to many world issues which sell for much lower. I've got one of the Iceland Althing millennium sets, in the original case, of which not too many were made. It cost a few hundred US dollars. And a Kiribati 10c coin with a total mintage of 20 000, in specimen condition? Cost me 25¢ US.

"Rare" (not many extant) is one thing. "Scarce" is the product of "rare" and "desired".

Just an additional comment on Numista and the rarity rating. I believe the "score" isn't an objective evaluation of absolute rarity - just an indication of how many people have logged that coin to be in their collections. A coin with a mintage of 10 where one person logs it will have a lower score than a mintage of 1000 where nobody has logged is as being in their collection.

So it's use it to be broadly indicative for most coins - but obviously at the extreme ends the formulae throws out whacky results.