Well, let me enlighten all you people out there, as to ensure you don't get scammed with a dud/copy Cart.
The only true way to ensure the cart is authentic is to look into the connection port, (where the game connects to the console,) which looks like a row of copper coloured lines.
If you follow these lines into the small area just before where the plastic stops, (its quite hard to see if you don't angle the cart right) you will clearly see "Nintendo" etched into the circuit board.
This is the only true way to ensure you buy a legitimate version of a Cart. I have not seen one copy yet with this etched onto the board.
Remember its actually impregnated on the circuit, and as yet I have not seen any copy carts with this on.
Also look out for non standard screws which hold the cart together. It should be a proper tri-shaped screw (these need a special screwdriver). If you're not sure what I mean, look at your console, these also are held together with these special screws.
Hope that helps some of you stop being scammed.