I'm more preferential to buying gasoline without the added ethanol rather than worrying too much about the octane level. As many have stated, they get by just fine with 87 octane.

Here in north GA I've got a bunch of stations on speed dial which have special pumps where, for a nice price increase, you can pump pure gasoline. I'll take that any time I can plan to need gas near one of those stations.

When on the road and forced to buy the ethanol crap, I pump 89 and say "screw it."