SD price drops have been due for a while. They had been at a fair price premium to CF, and more and more products are using SD cards. AMD has also said their flash side has underperformed recently, perhaps pointing to a general weakness in the market. Besides, the larger factor has probably been emergence of higher speed SD cards which lead some retailers to dump their stock of slower cards.
In all, SD pricing behaviour is probably closer to SATA HD prices than DDR prices. As larger capacities are introduced there will be a general downwards trend.
The DRAM market is much, much more volatile. Earthquakes, FUD, and seasonal effects all take their toll. Like with the stock market, the easiest way to lose money is to try to time the market. If I had to guess though, I'd say prices will probably stay steady for a while longer -- the school rush is over and X-Mas is a ways off. Plus, neither Dell nor HP appear to have RAM offers on their desktop builds (I'm assuming that they offer as a promotion whatever's cheapest to them).
So that's just a longwinded way of saying, who knows? If you need it, buy it -- if you want it, just wait until you need it. But keep in mind that an earthquake, war, port closing, or typhoon could always drive prices up.