Frontier Airlines is offering a two-day sale with deals as low as $11 for a one-way flight.The deal is available until July 29 at 11:59 p.m.Tickets are on sale now at FlyFrontier.com. “To help consumers celebrate the remaining days of summer or get a jump start on fall and winter travel plans, we are offering a sale unlike any we’ve offered before,” said Daniel Shurz,