Ebay has sister sites around the world, and apparently if you are registered on one you are registered on others.  So today I went to eBay.it, the home of eBay in Italy and searched on Pioggia di Pietre.  I found a bunch of sellers selling stone rains, and a couple had some of the ones I wanted (but shipped only to Europe.)  So I sent out 6 feelers on Italian eBay this morning to sellers who had stonies in stock.  Hopefully something will come of that!

Followup: My Italian eBay feelers have netted me a lead in Italy who says he has 5 of the 6 Italian Stone Rains I need and possibly some of the Japanese!  Stay tuned!