@erikalui, while I do think we should ban selling gift cards and you clearly do not this is not the subject of this thread. I do agree it's arguable and I don't want to even get into that.
As stated on OP the subject here is stopping the sellers who clearly sell illegally obtained cards. It seems to me you agree on that.
Yes, I too agree such sales should be stopped and users selling such gift cards should be warned and negated so that they stop such sales. Also, buyers should be given some kind of warning so that they too refrain from supporting these sales.