In a completely selfish way, I don't care about bootlegs. Any amount of research into an item (and the seller) will show he's "iffy." Bootlegs don't hurt the legit seller. One can argue that it drives down the price of GBA games but if you make it clear that you're selling a legit game, there isn't a problem.
In the same selfish way, if someone BINs your memory card for $3 and sees later you charge $16 for shipping, that's their problem. But that loss to eBay will eventually be spread among all sellers, those that circumvent fees and those that list items completely legit.
And you're not losing that much money. Maybe $1 per item. :? If that's a lot to you, charge a dollar more for shipping. It's still, in a way, circumventing fees but it's really not noticable and eBay isn't going to care.