Goodoldgold had a great site. It is obviously pretty labor intensive to profile the diamonds and present the info like he does. I wish more people did what they do. I doubt the price will budge much.
Price out a stone at a local jewler. Cut quality aside they would probily have to knock off a lot to meet online prices. At least that is what I have found. With my quest for an emerald cut, I have seen 30-40% differences between online and in the store.