What Is Really Considered Low Mintage.

Lots of information.

The "low mintage mentality" becomes a self-fulfilling prophecy. If I'm into Mercury dimes, you can be sure I've got several of each of the lower mintage dates/mintmarks. Not because I have holes to fill, but because "they might be worth something someday". So as a single collector, I may have 10 of a particular semi-key. If all mercury collectors do this, then it becomes rarer and rarer.

A lot of the comments above assume that set collecting will remain popular and I'll want to pay big bucks so I can fill the last 10 holes of whatever set. I'm pretty sure there are fewer and fewer Barber set collecters because they are becoming too expensive for a large percentage of the coin collecting community. The market will adjust accordingly.

Mintages mean nothing without demand. I know. An old saw. Somebody mentioned "cherry pickers". I also think of those error hounds with their microscopes. Who cares if the "E" in "States" is slightly doubled? It's truly very rare, but try selling it.....

and finally, FWIW, coins are NOT a good investment.