If Spirit Airlines goes out of business, your tickets with the carrier would become worthless. That's the risk hanging over the ultra-low-cost carrier as it searches for a buyer but has yet to secure a deal. The airline has struggled for years to turn a profit amid changing traveler habits and raising costs; reports say the oil crisis triggered by the Iran war could be the nail in the coffin.Basically, at the moment, it's a gamble.A merger or acquisition can mean that tickets are honored or rebooked onto th ...