Spirit Airlines offers roundtrip flights to Chicago from select cities in the U.S. with prices starting at $66.20, as provided by ShermansTravel. That $2 under last week's mention and the best rate we've seen for fares to Chicago. It's also the lowest rate we could find for select routes by $12. This price is valid on flights departing from Minneapolis, MN, (MSP) with arrival in Chicago, IL, (ORD) on September 16 with return on September 24; prices vary depending on the departure cities and dates chosen. Book this travel deal by July 25 for travel Tuesdays and Wednesdays September 1 through October 31. Click here to see more routes.