Spirit Airlines kiosks at New York's LaGuardia Airport on May 2, hours after the carrier shut down. Leslie Josephs/CNBC BALTIMORE/NEW YORK — Spirit Airlines was hours away from its final flights Friday afternoon. Jeremiah Burton was hours away from his first. "It's my first time flying," Burton, a 45-year-old air conditioning and heating technician, told CNBC at Baltimore/Washington International Thurgood Marshall Airport on Friday, shortly before he was scheduled to depart for New Orleans to visit his daughter and her newborn twins. "To tell you the truth, I just went online and Googled the cheapest airline ticket," he said, adding that he paid about $500 for the trip late last month. He was scheduled to return on May 6. While Burton waited for his flight, Spirit was making final preparations to shut down overnight , ending a three-decade run that brought discount air travel to millions across the United States and as far away as Peru.…