Frontier Airlines has a one-day sale today, April 7 ending 11:59pm eastern time. There are deals for flights to Denver and elsewhere. Atlanta ATL has several destinations under $50 one-way. This sale is for an extremely limited travel period and dates depend on route. April 22 to May 13 is the travel period with more restrictive dates for some routes.
One of the best looking deals to me is Washington Dulles IAD – LAS Las Vegas round trip for $148.10 all-in during the travel period April 25 – May 12, 2015.
There is a $50 one way fare IAD – LAS in Frontier’s one day sale.
Return flight LAS – IAD is $98.10 on lowest fare dates.
$148.10 IAD – LAS round trip April 25-30, 2015 on Frontier Airlines.