Spirit Airlines is just short of giving away its flights for free. It's giving away its flights for 99% off.
The deal expires tonight at 11:59 PM. But, if you can jump on the Spirit website before then, and input the promo code 99PCT (all caps, no spaces), you can get a flight for 99% off. The only downsides are that you have to book travel on Tuesdays and Wednesdays only between January 12, 2016 and February 9, 2016 and there are some restricted routes seen here. Oh, and you do have to fly Spirit.
The discount does not apply to taxes or Spirit's Passenger Usage Fee that can run up to $17.99 per trip. However, even with these stipulations, you're still getting a pretty amazing deal. For example, a $237 round-trip ticket from Los Angeles to Boston came down to $87 when everything was accounted for. Obviously, that price is subject to change. Check out all the terms and conditions here.