About the knockoffs being the same... the difference between the real one and the knockoff that *I* have at least is the "Desktop Defender" program that the real one has. A little Ravage will appear on your screen and wander around and eat icons, and other things.
The KO, however, typically goes for only about 10-ish bucks on ebay when sold auction-style. It's a good compromise if you don't have the 50-ish bucks for the real one.
However, I don't recommend getting the KO if it's being sold for the same price as the real one. Not only is there the loss of a truly awesome feature, but it's the quality you've got to worry about when it comes to any knockoff. After a few months of usage and play, will it be broken? Will the paint have worn off?