Seems like you've already solved this problem.
As you've already discovered, it is NOT a federal offense to ship these items via carries such as UPS/FedEx, and that's what paypal/ebay may tell the buyer to do.
That is a possibility. (Though there may be some issue had with transporting counterfeit materials across state lines).
If this is the case, then demand that the buyer pay the shipping costs - up front.
Ease up on the whole "it's federal law" bit. We're not talking about shipping hundreds of bootlegs to a retailer. Nobody cares about a single bootleg GBA game being shipped. There isn't a federal prosecutor or judge that would even look at a case this small. When it comes to the law, there is no "That's not how the world works". It's just not that black and white.
Except that it is black and white.
Now, if you're talking about if one would get caught or if one would get prosecuted - of course, that's a different story. But the law itself is black and white. That's why we have the great justice system we do. Laws (generally) are clear, but prosecutors, judges and juries are there to determine intent and decide if punishment is necessary.
My point, however, is valid and would hold up in any court of law - Anyone (company or otherwise) that tries to make breaking the law a condition of an agreement is making an illegal agreement. Period.
1st off, you cannot de-authorize your PP account without actually talking to paypal. Again, you've signed an agreement with them. It's very unlikely that your bank or CC company will block transactions from a specific vendor.
Which is why I've said that. MULTIPLE TIMES. The call is simply to lay foundation.
They will instruct you to close your account and open a new one if it's a big concern. Even then, PP will pursue you for the money. They are relentless fucks, even with an amount as pithy as 15 bucks.
Let them. If you're determined enough, you can then bring them to court yourself. Especially if they attempt to attach anything to your credit record.
Want some free money? PayPal has some pretty deep pockets.
The "big difference" is that any transfers which may take place regarding this transaction aren't going to be considered "future transactions", since the transaction itself has already taken place.
The transaction involving someone selling you counterfeit goods. Which is something you 100% have the right to dispute and will win virtually every time.
"See how quickly they back off" and totally deny your claim is more like it.
... still waiting to hear your stories involving being duped into buying counterfeit goods. Because I've never had this happen.
Congrats to you on winning 3 fraud dispute chargebacks. That's not the norm when it comes to such things, but rather the exception. Keep in mind that both Mastercard and Visa have recently re-written their fraud chargeback policies. Filing 2 or more in a given time frame puts you under the microscope. Just something to keep in mind.
...and still waiting.

I'm not trying to completely discredit your methods, Bob. I just feel the buyer should be aware that such aggressive tactics aren't necessarily the best route for everyone to take.
Aggressive tactics are the only method that will yield results. These resellers *know* no one will follow up on them... and that's how they get by with it.
You obviously have VERY strong feelings about bootleg games, and that obviously affects your choices regarding the resolution of a situations like these (as evidenced by you insistence on either destroying or reporting the items in question and your assertion that the chargebacks "aren't for the money".)
Yes... Bootleg resellers are, as far as I'm concerned, the scum of the hobby. Now, I give a little leeway to those selling reproductions of games you can't buy (like, say, English Mother for the NES). While I won't do business with someone like that, at least they're honest about what they're selling and they're providing a service to fans who can't get what they're looking for any other way.
But for bootleggers of common DS and GBA titles? Screw these folks. They're not trying to help anyone but themselves. They're doing it in a dishonest fashion with the singular intent of ripping off everyone in the process.
As for destroying the merchandise, I do that for myself. The goal isn't to get "free stuff" - and if you get your money back *and* keep the merchandise, then you're cheating the system in a big way. Destroy the merchandise and you gain nothing from the entire transaction.