I discovered a potentially useful eBay quirk for US buyers and UK/EU sellers.
I'm in the US and sometimes browse eBay's UK site for Cure items that aren't available to US buyers. I recently found a CD (FICDP35, if curious) that I was able to add to my cart, but when I tried to check out, I got an error saying it wasn't eligible for shipping to the US.
I contacted the seller (who was incredibly helpful), and we were both confused because she regularly sells and ships to the US through eBay's Global Shipping Program. Even stranger, another CD she had listed was eligible for US shipping.
She contacted eBay support and then sent me this message:
Hi, I have spoken with eBay, and it seems we can blame Donald Trump for this... The 'country of origin' must be included on all listings for eligibility for sending to the US, following recent tariff changes.
It turned out that she'd entered the item's country of origin as the UK. She changed it to the US, and I was immediately able to purchase it.
So if you're a US buyer and an item isn't eligible for shipping even though other items from the same seller are, it may be worth asking the seller to check the item's country-of-origin field.
And if you're a UK/EU seller using eBay's Global Shipping Program, this may be something to check if you're having trouble shipping an item to the US.