I believe Mohawk is the only Ethanol based gas dealer on the Island, or at least I hope so. Be careful as the ethanol will destroy older motors which have plastic parts throughout the fuel system, and worse you will lose more than 1/6 of your gas milage running it. As far as Octane, all gas is the same when it is refined. But the difference is after refining individual service companies will put in additives to bump up the octane amount. Basically a similar product that you get at a retail store <ie. Octane Boost>.
Purple gas is the same as farm gas, also named dyed gas. I know it used to effect very hot running two strokes by leaving a film and causing premature engine wear, but I have no idea on fuel injection systems nowadays and how it effects a 4 stroke, as I am not a mechanic. Sometimes saving a buck costs you alot more in the long run.