Its a sin against the 4th commandment "thou shalt not steal", to copy DVD's.  I would think that it would be knowingly purchasing stolen goods.  

The product of a man's art, skill, painting, writing, etc., belongs to him to the extent that he is entitled to derive reasonable profit from his labour.  Consequently the law of patent rights and copyright is just...

Interesting argument Tele.  I have to say that I am on the fence on this one.  Especially since I've seen people post on forums that they paid $60 dollars for the dvd back in 2008.  Leads me to believe that whoever is selling it on ebay is looking to make a 500% profit on it.  I'll ask Father tomorrow after Mass.

If the product is no longer available "new", then the person who created it is done making his money.

Sometimes used markets support the new market, but that doesn't seem to be the case in this situation.

IS IT PERMISSIBLE TO MAKE COPIES OF CDS AND DVDS THAT ARE SUBJECT TO COPYRIGHT?

The Church has always defended the right of private ownership, as guaranteed by the natural life, and entirely necessary for the common good of society. This right does not only include material objects, commonly known as private property, but also includes such spiritual things as a man’s reputation. It consequently also includes the fruit of one’s invention, hard work, creativity, such as books, music, and manuscripts at least before they have been made public. It is quite simply theft to take and copy such items without the authorization of the author, who has ownership over them.

However, the usual difficulty arises over such books, articles, conferences, music, and movies that have already been made public. The common opinion of the theologians is that in the natural law they still remain subject to private ownership, and that consequently they cannot be simply pirated. However, it would be contrary to the common good if they would remain perpetually subject to private ownership and control. Positive civil law recognizes this and admits the existence of copyright laws that forbid copying of such articles, music, movies and the like without the requisite authorization of the person who owns the copyright. However, for the common good there is a limitation on the duration of a copyright if it is not renewed, after which time the intellectual work enters the public domain. These laws are just and consequently bind in conscience, so that a person who deliberately infringes them commits a sin against justice which is either mortal or venial, depending on the gravity of the matter.

This being said, the permission of the copyright owner can be presumed if the copy is for a small item and for only a single copy or a small number of copies, which copies will not deprive the owner of any significant income. In such a case, it would not be reasonable for him to object. Thus it is permissible to photocopy one or several pages of a book that is under copyright and still in print, but it is not permissible to photocopy the entire book, thus depriving the bookseller of the sale of a book. In like manner it is permissible to copy one or other song, or a part of a program or CD or DVD. It is not, however, permissible to copy entire CDs or complete DVDs that are under copyright and still available for purchase without authorization of the owner. In general it would only be light matter and a venial sin, but to do it in large quantity and make a business of it would certainly be a grievous sin as well as a criminal act. It would be different, however, if the items were already in the public domain or if the copyright owner’s intention was to allow some limited access to this copyrighted material.

The downloading of programs, music, and material from the Internet needs to be considered according to the intentions of the owner of the website. In general, it can be presumed that if the material is put up on the Internet without any restriction and by a person who has a right to the material, then he is by the very fact making it publicly available. In general, it is permissible to download and use such information, since it can easily be limited by passwords, credit card requirements, and the like so that unauthorized persons cannot access it. Consequently, if the website does not expressly forbid copying the music, articles, and other items, then it can be copied without scruple.