Well I have a passive 3D tv from LG and got 7 glasses with it which are the same as in the cinemas and cost nothing. Now what you can do with those is in splitscreen games like mod racers and motorstorm you put 2 right eye glasses in one frame and the 2 left eye glassen in the other and you both see your own screen in full!
This is basicly how that special sony tv works but then in a much cheaper way