I know that the express card that Sony XDCAM Ex uses is from the generic express card and that any generic express card will not work with this camera. What I like to know is, what are the differences? Let's say this card from Lexar compare to the express card from Sony and SandDisk. What's the big difference between the Lexar which around $200 versus $900 from Sony or SandDisk? I still can't believe the card itself is that much from Sony and SandDisk.