http://www.nrel.gov/vehiclesandfuels/pdfs/sr368051.pdf

Andy, if you didn't find this in your searching, this has a lot of information about CN of different chemicals. Finding a chemical that is cheaper and easier to handle than ether still isn't easy. I think the kerosene and octyl nitrate blend is good as long as it starts reliably. Diesel No.1 should be extremely similar..

It seems that there are chemicals that have high cetane numbers but also very high auto ignition temperatures. Castor oil is one and Biodiesel is another. If the in cylinder temperature doesn't get hot enough it won't fire, so CN isn't the only thing we are looking at. In an injected diesel cylinder temperatures are high enough to run B100 without problems, but I don't think it will work in our engines. The link above says the ether we use has a CN of 140-160.