Very true, most of the time. You will also have to read the EULA or any licensing agreements that apply to the product to see if they prohibit the resale or sale of the product. An example would be Rosetta Stone, which under the first sale doctorine you should be able to resell it. However, Rosetta stone EULA prohibits "2. TRANSFER: Licensee may not sell, rent, lease, loan or sublicense the Rosetta Stone Product.", and they have enforced this taking down auctions on Ebay of people who were not authorized resellers and instead attempting to resell their own copies.
Hey guys it is pleasure to meet you but I want to ask you about something. You see, few days ago I found site called buy play, where you can buy cd-keys. Do you think it is a good idea to buy from there?