For the love of god, get a quality card. My sister bought a memory card a year ago from a less than reputable dealer and after several months of use this card eventually became unreadable so she gave it to me. So this weekend I had to recover images from the corrupted card. It took about 6 hours. But I was able to recover a fair number of images from it. After getting that done, I ran a scan to check the integrity of the cards memory cells and i'm amazed I got anything off it in the first place:
This was an 8Gb memory card...and only 30mb worth of memory cells were capable of reliably holding data. I pulled the card apart and traced the origin of the memory module from its serial number. The NAND flash module from the card appears to be made in Korea by Hynix, which is a manufacturer that also makes RAM modules for computers and is also on the list of manufacturers I flatly refuse to work with, because of the high failure rates of their products.
Never buy cheap knock off memory cards.