That's tied with the best price we've seen on Frontier and the lowest price we could find for select routes by at least $5. Buy Now at DealBase Tips On the DealBase landing page, click "Frontier Airlines" in the top line to see this sale. We found this price on flights departing from Atlanta, GA (ATL) with arrival in Denver, CO (DEN) on November 12. Book this travel deal by November 6 for travel from November 8 through December 18. All prices, dates, and booking details were valid at the time of publication.