Picture the scene: You're at the 2005 National Association of Broadcasters show in Las Vegas. Barely able to focus after half a dozen yards of frozen marguerita, you stumble across a stand selling sound effects CDs. You spot one called "Guns" and read the back: "Choose from more than 60 different guns, rocket launchers and hand grenades. This library includes North American and European models, vintage black powder guns, World War I and modern weapons, and full size military munitions". Then you listen to this [mp3] awesome preview. $500 for three CDs! Great! I'll take 'em!
Two months later, you realise what you've bought and put it up on eBay, with the description "Our customer realized they had no need for them." Come on, it could happen to any of us...