Due to my satisfaction with the 4GB Micro SDHC from Sandisk, I decided to upgrade to an 8GB version. The 4GB I bought at my local BestBuy, but this time I wanted to save a few dollars, so I ordered from Amazon, in particular the seller "Digital Media Source."
Once I received the product, I noticed that it was in what is called "Bulk Packaging," (just the card inside a plastic case with no sealed manufacturer packaging)not RETAIL packaging as the item description suggested.
Either way, I figured I'd use it. I copied roughly 7GB's worth of music and video over to it. I then inserted the card into my HTC phone. After two days, the card was corrupted. Corrupted in the sense that I had to reformat it. The VERY NEXT day, the same thing happened! Two days after the second corruption, it happened again. I had not experienced this with my 4GB that I bought retail at BestBuy, EVER - It has not corrupted on me to this day.
So I decided to contact Sandisk for support, and they asked me to email them macro photo shots of the card, so I did. Two days later, I received an email from Sandisk support telling me that the card was in fact counterfeit. He stated that the simple fact that the card came in "Bulk packaging," is almost enough to tell whether it's counterfeit or not, but that what led him to his conclusion was the imprint of the Sandisk logo and the other text on it. He suggested I get my money back from Digital Media Source, here on Amazon, but I have not. I've decided to just copy my contents over to it whenever it corrupts as an 8GB Micro SDHC card costs much more at a retail store.
So my overall suggestion to you as a buyer, is that if you are looking for a legitimate card, to make sure that what you're receiving is in retail packaging. If you pay as little as I did, under 15 bucks, you might be getting a counterfeit card. You ultimately get what you pay for.