Prices of a particular type of RAM follow a pattern. They start out high and slowly go down. Since they are a commodity item, their prices have ups and downs depending on the economic situation, new uses for the product, lawsuits, and a million other variables.
At some point, when new technology (DDR3) is introduced, they reach their cheapest level. Everybody makes them, the manufacturing technology is fully developed, and there's lots of inventory.
Then, as RAM makers shut down their old lines and open up their new lines (to build DDR3), the prices will start to slowly climb.
If you luck out and time it right, you can buy RAM, use it for a year or two, and sell it at a profit. If you are good at that, become a stockbroker.