Are Rare Date Coins Valuable?

There is mintage rarity and condition rarity and absolute rarity.
John1

Price comes from supply versus demand. US coins enjoy practically unparalleled popularity, and are thus easy to articulate values for. The same goes for most issues of Western Europe, plus many/most Spanish or English colonial coins from before WWII. Indian, Chinese, Korean, Vietnamese, and Japanese coins are also on the rise.

When dealing with obscure collecting fields, rarity seldom guarantees a high price, since many will be content with a type collection only. The market is also over saturated with manufactured rarities; entities like the RCM and Franklin Mint churning out hundreds of types of "rare" coin with mintages in the hundreds to low thousands - there is too much to collect, so they take a massive hit in the secondary market because most collectors will take a pass on anything less than a steal.

It's only worth what someone is willing to pay

Here's a fun example from one of my favorite quirky off the beaten path countries:

https://www.NGCcoin.com/price-guide...duid-1484975

Bundi was a nominally independent small kingdom in India that still relied heavily on the UK, and in this case put Victoria's name on their coins. This is a long run of coins, bearing an explicit AD date, and overall scarce enough to be worth a good deal more than melt.

Of that long run, are there key dates? Almost certainly. But nobody cares to complete the set so they carry zero premium. In fact, I have never heard of anyone even attempting a set!