Not everyone's DS's will have problems. (Just saying)
I've seen one dropped on the concrete, skid across a parking lot, in the rain. It was absolutely fine. Nintendo's products are well made, so don't worry about that. Mine has had zero problems.
Back to the original question. Our target has DS's in all the time, check there. I doubt you will find any deals since they are so new. In March when the PSP comes out I expect that there will be some special deals on the DS as well as new colors. If you can wait till then, it might be worth it. A ton of games for th DS are coming out then as well.