You haven't given enough details to determine which of the following is the case (and any of them could be):
His decision to do GSP is unfortunate for you only because he's doing it WRONG, as your living in the US should not be affected by this decision.
His decision to do GSP is unfortunate for you because he's doing it RIGHT, but your living in Canada means you get as much shaft as if you lived in Timbucktoo.
His increased shipping charge has nothing to do with GSP, in fact he may have had GSP enabled all along and you just didn't know because you had no reason to check.
You didn't say where the seller lives nor where you live, so that's part of what's confusing. But your title maybe (?) suggests that you both live in the US, if you were able in the past to get purchases from him shipped in an envelope with a postage stamp instead of a shipping label. Your original post makes it sound like you might live in Canada ("I've also gotten every single package he's sent, so in my case it's not as though these letters to Canada are getting lost in transit"), but your subsequent reply talks about YOU shipping TO Canada, so again, very confusing. I DO understand exactly why the relatively low cost of shipping between the US and Canada would make an impact on deciding whether to do GSP--no need to spell that out. But if my original assumption about you both living in the US was correct, then I don't understand why your shipping cost buying from him would change.
You also didn't explain what his stated shipping charge was in his listings before he started doing GSP (was it $1.00? $3.00? Free?), nor what it states now. $13? Regardless of where the buyer lives? Or are you seeing $13 as a calculation because you live in Canada?
I get that from your prior purchases you knew it would take a while to receive the items and you wouldn't have tracking and whatever, so I'm not confused about that. But I don't see how expanding his buyer base to international buyers would change how much YOU would have to pay, or at least not the dramatic $13 amount that you say it would now cost for each nearly-weightless auction item that you win. Again, this is assuming you both live in the U.S. Even if enabling GSP in listings required that each item be shipped with a First Class label, even within the US, the most you would have to pay would be the $3-4 rate for a one-ounce package label, depending on how far apart you and he live. I sell jewelry including vintage costume pieces with a $4.25 shipping charge (a bit more than enough even if my buyer is in AK, HI, GU or PR). And I have GSP on my listings, so if the buyer is in (say) the UK or Russia or whatever, then yeah THEY have to pay whatever Ebay tells them, but I still just purchase the <$4 First Class label, which it costs me to send from Mobile, Alabama to the Erlanger, Kentucky Ebay hub, same as if it was a U.S. buyer.
Here's why I mentioned the 3rd possibility, that your complaint has nothing to do with GSP. IF what you're seeing is his listings now having a STATED $13 shipping cost, and they didn't before, it could be that he just got wind of the trick that some sellers do with auctions. That is, to disguise their starting bid with overpriced shipping, rather than make their starting bid an honest minimal amount they would like to receive for the item. Setting the starting bid silly-low, like $1 or $5, CAN be a great way to attract lots of eyes and get lots of bids, which increases its' showing in search results, via the algorithm. It certainly works for me, but then I'm a TRS with 1-day shipping and excellent feedback, lots of my buyers are repeaters who have me in their 'Saved' list, etc. Someone with lots of negs for slow shipping, or just lots of people who skim past his listings because they remember their bad experience with him .....yeah I could totally see him getting sick of having to let valuable items go cheap because he's down to only a few patient buyers like you, and just making a stupid choice to jack you on shipping (and lose you), rather than improve his practices to clean up his reputation. If that's the case, it's just as foolhearty as what you think he did, but not a case of GSP being the foolish choice.
