gas price surprise

Driving through Hot Spring, SD, I needed gas.  I noticed a sign that seemed to have the prices mixed up.  When I asked for clarification, I learned that the 85 octane gas is truly more expensive than the 88 octane gas.  Why?  The 88 octane gas has 10% ethanol.  I checked my car’s manual and filled up.  Ethanol, glad to meet you.