I noticed this a while ago, but only thought of posting it up now. These used to be around $3, but now less than half the price. The card reader comes in very handy, especially for those with R4 DS. It's reliable, small and very cheap.
Alternatively, you could get this one:http://dealextreme.com/details.dx/sku.11294
It is thinner than the other one and i end up putting it the wrong way round in the USB port sometimes.
Either way, I have both, and they are great. So far no problems with the two i have. :)