I had bought a pack of these from YakyuShop back when the set originally came out. Well, I say "pack" but it was actually sold in little boxes. Each box contained four cards - three base set cards plus one "special" card - along with a player pin. I think every box contained the same ratio of base cards to "special" card so the "special" cards are three times as rare as the base set cards.
Here are the cards that I got:
Here's photos of the front and back of the box that the cards came in:
And finally here's the player pin I got in the box:
It was kind of an odd set and the JPBPA never issued another one. I'm not a big fan of sets that don't have the team logos (I never buy anything from Panini) so this was never a set i was real interested in completing. Ryan on the other hand has the complete base set and posted all the cards a few years back.