I find it pathetic that anyone can think sales will double because of a $100 price drop, you think that the extra 100% of sales is coming from people that were holding out because they didn't have a spare $100 on em?
If someone would pay $499 about 75% of them would pay $599 if that were the only option.
Hence I predict a 25% sales increase for the month.
Amazon is not a reliable indication of sales, Wii is almost always beating DS but you never see that on the charts.