Luckily, the GSP program is still a choice for the sellers. 50%+ of my buyers are overseas and I send stamps and covers anywhere via regular USPS mail mostly without issue and 2 oz shipping with the nonmachineable surcharge is still under $3 US. I've sent mail to Haiti, Ethiopia, Ukraine (during their current war), Pakistan, Egypt and even India, Russia, Brazil and Italy without issue.
Mailing internationally is not hard at all. Even custom forms are a snap if needed. Determining postage is easy can be since everything you need to know is online. Just get yourself a scale if you don't have one yet.
Unfortunately,
ebay has pushed the GSP program unto sellers in the recent past very hard and even tricked them into it via "seller updates".
ebay sold the idea to new sellers and those weary of selling internationally as a "risk free" way of selling without mentioning the undue burden of extra costs on the buyer. Please don't blame the sellers as they were duped and sold a sack of lies. If you come across a seller who has the GSP mailing costs - please message them and tell them that's the costs are too much and you don't buy from sellers in the GSP program. Hopefully, more will opt out of it if they can - in the past
ebay has made it difficult to turn it off.
For those sellers like John Becker who say "I won't sell internationally". Guess what,
ebay will force you through the GSP program if you haven't selected any international mail options.
ebay will pick one for you and only one option - theirs.
The GSP program also has other unspoken issues - collecting custom fees from the buyer on items that probably do not warrant such fees, repacking shipments (may or may not be damaged as a result) and seize of items the courier believes cannot be shipped to another country. In the latter case, buyer is reimbursed, seller keeps the money, but item is not returned to seller and may be deposed/resold by the third party. Nice draconian escrow service there. No thanks.
If
ebay were to make the GSP program mandatory, I will leave
ebay. It's a deal breaker.