That's because, for most games, the sales drop to a trickle after the first couple of months. At some point after the first obligatory expansion, they make a bundle that includes the games and expansion and sell this as "Insert Game title Here" Gold. This is a last ditch effort to get a few bucks off of the game. By this time, it isn't moving at all. They usually don't make a lot of money off of the Gold Edition, but then again, it doesn't cost much to repackage (often without manuals).