ChrisC,
You're right, the consumer has to be careful. I always confirm that it is an original and not a "copy".

The official position of both AMAZON.com and E-Bay is tough. Copyright infringement is not tolerated. They turn in these sellers to the appropriate authorities, and deny them seller rights. So they are working hard to try to stem the flow of unauthorized copies of films, DVD's, Cd's, and computer software. The fines in the U.S. are stiff ($10,000) for this behavior.

Saludos,
Carmen