Here's how the world is supposed to work. You buy something, you own it. Once you own it, that means you can sell it. You might sell it for a much lower price than what you paid for it, but you can't expect a Mad Men season one DVD to turn into a week's worth of malt liquor breakfasts without sacrificing something in the process.
It's a rule called the "first sale doctrine" that allows you to do this. If you're surprised to know that you need legal protection to hock your Blues Traveler CDs at a garage sale, you'll be even more surprised to know that a case before the Supreme Court right now could take that legal protection away.
Supap Kirtsaeng, a grad student at USC, was sued by textbook publisher John Wiley and Sons after he sold eight foreign editions of their textbooks on eBay. See, Wiley and Sons sell their textbooks overseas at well below the anal-rape price point that most textbooks are marketed at here in the States. Learning from a grossly inaccurate history book that Christopher Columbus invented America is only worth $300 if the people you're selling it to can afford to pay that much.
Like these dipshits.