The general rule when it comes to SD cards (and other flash memory) is that if the price is too good to be true, it's probably fake. I can't be certain, but $78 for a 32GB Class 6 sounds too good, considering I recently got a 16GB Class 4 for $45 (double the capacity for less than double the price doesn't seem right, not to mention the bump in class). The last section of
this article (the heading in bright red) tells more and links to some more comprehensive resources.