I just read a fascinating story about investigating a bad batch of Kingston MicroSD cards. Some of the things I learned:
Toshiba and Sandisk co-own the same fabrication facility.
Samsung does not sell their own cards retail, only through resellers who re-brand them.
Kingston does not appear to manufacture their own memory chips, but repackage Sandisk/Toshiba chips.
A complete SD card's cost is nearly identical to the raw Flash chip itself, meaning that the controller and package is provided essentially for free. This is presumably because the cost of testing a free-standing Flash chip is dramatically higher than testing a complete SD card.
Chinese fake SD cards are impressively made and packaged.
How to spot a knock-off SD card (appearance irregularities and card ID data).
Z-A-Recovery is useful for recovering strange data from that re-sold, fake SD card you bought at a Chinese market stall.
I'm certainly wouldn't say that Kingston SD cards are bad, but I will point out that I don't see any reason to move away from my quite affordable Sandisk, Lexar, and A-DATA cards.