Here's a link to gas stations that have pure gasoline.
You could get it here.
Now if only we could afford that pure gasoline!
I've used the site for years to plan trips in the T. In general, marinas are good places to get ethanol free. Not many roadside stations carry ethanol free in less than the pricey 91 octane, but a few do. One in Girard, PA, has 87 ethanol free about the same price as the ethanol stuff.