Spirit is at it again with a $50 off coupon code. Enter 50OFF in the promo code box on Spirit's site by midnight ET July 5 and you'll get your fare for $50 less than you will find on any other site, such as Kayak or Travelocity. Flights to/from Detroit get $40 off. We have found in the past that when combined with one of Spirit's wacky $7, $9, 1 cent, or whatever fares that on some routes the promo code discount actually wipes out the entire fare,  so that your fare ends up being zero plus tax. We've even seen cases where the taxes are even wiped out!