Hey all, wanted to share my recent eBay memory card experience. I purchased an 8GB 60MB/s Sandisk CF card from one of the many Hong Kong based eBay sellers. They had a 99.4% rating and their feedback appeared solid, so I went for it. It arrived within a couple of days (how the heck can they ship so quickly for free?!), in a reputable Sandisk package. The card was in the plastic card case, which was inside a sealed plastic package, which was inside a chipboard box.
Tossed the card in the camera, formatted, and went out shooting. My previous card was the Ultra II, and while it worked okay in my old Rebel XT, it choked on the files my 7D was trying to write. This new card was handling the full 8fps with no problems, and I was a happy camper.
The next day I become a member of this forum, start browsing around, find this sticky, and start feeling a bit queasy. I searched around the web for more info, and finally contacted SanDisk online help. They had me provide the serial number, and then send in some pics of the card. A follow up email from them revealed that the card was a legitimate Sandisk card. Whew! Bullet dodged, but man what a stressful couple of hours there.
So, I suppose my point is that some of these eBay merchants are reputable, but unless you've already had prior experience with a particular one, there's no way to tell. In the end, I saved about $8.00. Totally not worth the anxiety that followed. My next purchase will be with an authorized dealer in the states. However, I can fully recommend this particular eBay seller, user name "sinceritytrading". My transaction with them was as good as it gets on eBay, and if I was looking to purchase the same card, I would use them.