If you are still confused about the roles of RAM distributore (G. Skil, Patriot, etc) and the chips they may use for their various retail RAM lines for the purpose of marketing (Dominator, Ripjaws, etc.) send and email to the RAM distributors support and ask specifically what chips are used to make their RAM. Someone on the Forum may know, but I don't think anyone will be telling you anything more detailed that my suggestion. What makes one chip more expensive than others? Answer is, depends on how much the RAM distributor paid for the chip. The distributor would have to pay more for superior chips. Those chips would be called Dominator, Ripjaw, Ballistic, Hallucinator, etc. Maybe someone other than the RAM distributor can tell you Micron D9's are used for Ripjaws, I don't know.
For examle. Here is a DDR2 list stating which chip is employed on which RAM distributor's DIMMs.http://ramlist.i4memory.com/ddr2/