Recent Purchase - I Can't Resist Clemente Kellogg's Cards from Puerto Rico - There are Some Questions

I purchased the two cards listed below last week.  The corners are not great and the back has a bit of discoloration on one edge.  But, I can't resist buying these cards.  They don't show up often.  I've got them in the package and opened now.  It's time to try upgrading the opened ones now.

These cards are part of a three-card set issued in Kellogg's cereal boxes in Puerto Rico.  These don't seem to show up often since they are not part of a mainstream set.

Whenever I go to the National or other larger card show Clemente cards are always among the most popular.  I've yet to find one of these cards at a decent price at a card show.

There are some great advertising pieces made in conjunction with this set.  I am on a mission to acquire those items.

I checked PSA Population Report and only four of these cards have been graded.  That surprised me since Clemente is one of the most popular former players.

Were these cards in short supply?  Did dealers somewhere get leftover stock like they did with some other Kellogg's offerings?