this is common in our area, Iowa and up into Minnesota / Wisconsin. It is 88E15 versus 87E10. Usually it is $0.20 or more cheaper. If it isn't I usually use 87E10 because it will get slightly better mileage in our Chrysler T&C resulting in a more cost effective solution.
Because its sheetz.
the other day I was there and the super 88 was cheaper than the e85 and 87 octane.. which makes no sense because its blended from both at the pump.
That's one of the FEW times I've seen E85 cheap enough (relatively) to make it worth losing 25-30% of MPGs! Around here, E85 is usually only 20 or 25 cents cheaper than E10 87, making it a bit of a ripoff.