If you want ethanol free gas, go to an industrial chemical supply store and ask for 2,2,4 trimethylpentane. CAS #540-84-1 Earlier in this thread Mexicowander also referred to it as alkylate. Alkylate is the standard which motor fuel uses known as octane. It's really iso-octane. It has a MON (Motor Octane Number) of 100 and an RON (Research Octane Number) of 100. It won't have any detergents like polyetheramine (Chevron Techron) added to it so you will have to add that additive to prevent carbon buildup. 2,2,4 trimethylpentane is commonly found component in most gasoline. Bought in larger quantities it should be fairly cheap.
To learn more, search for Bruce Hamilton's 4 part FAQ on "Everything you wanted to know about gasoline." Be prepared, it's a little dated and very technical difficult reading for those without a general chemistry background.
Chum lee