Apparently our listings have not appeared in their search results using the default search (for quite some time now). They only saw items listed on the international site, not the US site. They had to use an advanced search technique that perhaps all users wouldn't know about. Savvy buyers would know how to do this, or just go directly to ebay.com and look there. Either way, international buyers DID find the items they were looking for.
Now, for an extra fee, you can have your item show up on the foreign site without any extra effort on the part of the foreign buyer to locate it.
Is it worth the extra 10 to 40 cents? I say NO. Buyers will find your items if they want them. This is just another nickel and dime attempt. In fact, I list items that plainly say US only, and I still get emails from foreign buyers wanting to know if they can bid, and some don't even ask - they just bid. So why should I pay extra when they're seeing them anyway. This is just to trick novice and newbie users into giving eBay a few more pennies of their profit margin.