Frontier Airlines offers select 1-way fares on select routes with prices starting at $15. (Click on "Frontier Airlines in the top line to see this sale.) That's tied with our mention from last week as the best base rate we've seen from Frontier Airlines. (It's also the lowest price we could find for select routes by $183.) This price is valid on flights departing from Miami, FL, (MIA) to Chicago, IL, (ORD) on January 7; prices vary depending on the departure cities and dates chosen. Book this travel deal today for travel on select dates from December 30 through January 28, 2015. Click here to see more routes.