That's the best price we could find for select routes by $5. Buy Now at DealBase Tips On the DealBase landing page, click "Frontier Airlines" in the top line to see this sale; we found lower fares within. We found this price on flights departing on January 9 from Atlanta, GA (ATL) to Islip, NY (ISP). All prices, dates, and booking details were valid at the time of publication. Book this travel deal by December 31 for flights through March 4.