Thanks for your advice/help guys;
I ended both auctions early. I really wanted only to remove the bidders I didn't feel comfortable about, but instead canceled the listings completely.
I was charged with the Ebay final sale fee, but after a chat with customer service, I had the fee reversed, so I lose nothing.
Since I listed the items, I changed my selling preferences to block all international buyers. However, even Ebay will admit that they have no way of blocking international buyers if they have a U.S. address listed as their primary address.
Funny thing happened while I was trying to decide what to do about the first item with the Mexican bidder.
My other item also received an international bid - from Baharan.
I have set my preferences to block international, and tagged the box 'apply to current listings' (or whatever the label is) but apparently that does not prevent foreign bids. Maybe these bidders have a U.S. address, but it just makes me feel very uncomfortable.
I will take your advice and list here or on QRZ or QTH, or maybe at an in-person hamfest. I would think that by now, outdoor hamfests are pretty safe for someone (me) who is fully vaccinated.
Or, I may just decide not to sell the items.
Honestly, my gut was not feeling very comfortable about the whole process of listing items on Ebay, despite my having sold a fair amount there in the past. I never had an issue like this before.
Another interesting thing happened:
Shortly after I had received an e-mail from Ebay informing me that my listings had been canceled, I received an obvious (seemingly unrelated) phishing e-mail from someone claiming to be Walmart.
I had not even placed an order with Walmart, but looking at the return address, I could clearly see that Walmart had not sent me this e-mail.
So now I'm thinking that perhaps my Ebay account has been hacked?
I have changed my pw and questions. Not much else i can do, but I have to be vigilent of fraud charges on all of my accounts.
Man, I really miss the days of just doing everything in person. We went to hamfests, and sold stuff at our repeater club's swap 'n shop.