This is nothing new. I worked at a small computer shop in a small town between 2005-2007. The owner treated memory as a commodity. He checked national ram module prices daily. Buying low, and selling high. He sometimes adjusted the module price on a per-customer basis.
I get that it's much harder to do that with online stores, where prices are published to multiple places, and for chain stores where the price needs to be consistent between locations.
