For real? SD Memory cards for under $15?

I've been checking prices online for 2GB SD cards for my new Canon Powershot 850 IS. Amazon has 'em for under $18, and the list of "other sellers" on the Amazon website are selling SanDisk for $15 and Kingston for $12. Is there a difference in speed, quality, or reliability from the $50-60 cards I've seen at the Circuit City, Best Buy and camera websites? Or are they actually the same cards with huge markups?

Will any 2GB SD card work with my camera? If not, what specs should I look for?

And what does it mean that some cards are "secure"? For my Powershot 850, do I need one that is secure or insecure? If I get an insecure one, will it need therapy?

I think some of the cheaper cards are not suitible for cameras due to a lower bandwidth. You should look for at least 10mb/s (or x66 speed) apparently. This is according to my boss at currys. We have people coming in and saying how expensive our sd cards our in comparison to the internet, our excuse is that ours are really fast. But it could be the case that only the SLR cameras actually need to fast cards.