I buy from 1saleaday.com (same site) all the time. I don't buy anything major (usualy cheap stuff like this), but I've had 100% satisfaction with them. However, if they screw up a order, I heard it can turn into a nightmare. Just other expereinces I read on the internet.
Biggest order I ever did with them was a 1080p upconvert DVD burner for $49.99. It shipped quickly and I was happy. Other items: memory cards, clip-on WA lens, another WA threaded lens set, headphones. All were good expereinces for me.
You need to watch them closely though. In this case, I think these are knock-offs, and the $4.99 shipping you'll pay is likely the price you pay for a 3-pack of these on any givien day.