Frontier Airlines is offering some of the lowest fares I’ve seen in a long time! Prices start at $19 (for Discount Den members) and $39 one way for non-members. Discount Den membership is $49.99/year and qualifies you for fare discounts year round. Signing up for the Discount Den program is a little tricky. You can’t just do it via a form on their website. You have to go through the process of buying an airline ticket, selecting a Discount Den fare, and then you will see a link to sign up. The $49.99 will be added to your total along with the airfare you are booking. You must travel 9/15-12/16 for this sale.