Potvin:
I know what you're talking about, but I don't see how you can do that with a s/n card, the seller knows which one he sold and which one a seller might return. That's also why I took pictures immediately and e-mailed them to the seller.
It was kind of funny, when on the phone with the SportsBuy rep yesterday when he finally looked at the pictures sent to the seller, to hear him say, "oh," in a similar fashion to how I reacted.