The vision of light rail connecting Tampa to other Florida metros seems light years from happening.Business and leisure travelers untethered to a car, however, will soon have another inexpensive, mass transit option for trips to Orlando or Miami. They can take a bus … a megabus, that is.Megabus, a city-to-city express bus service company, is expected to announce today that it's launching service out of downtown Tampa, shuttling passengers to and from Miami and Orlando. Its 81-seat, double-decker buses will run six daily arrivals and departures from the Marion Transit Center at 1211 N Marion St.Service begins May 15. As a promotion for the first week only, all fares will be $1 plus a reservation fee of $1.50. Beginning May 22, $1 tickets will continue to be offered daily on every bus, but the price will increase incrementally as it gets closer to a customer's departure date."It's a yield management tool we use just like JetBlue," said Megabus vice president of marketing Mike Alvich. "The next level could be $5; then $7. The highest fare may be $20 or $25 to Orlando; maybe $30 to $35 to go to Miami. But it's still very, very affordable, even if you have to book for tomorrow."Simultaneous with the Tampa opening, Megabus is launching service out of Miami and Tallahassee, joining the three Florida cities already in its network: Gainesville, Orlando and Jacksonville.A subsidiary of transportation giant Coach USA, Megabus.com launched its North American operations out of Chicago in 2006. Since then it has mushroomed to serve 120 major cities out of 14 hubs (including downtown Orlando, the newest hub, which will offer ready bus access to Disney and other theme parks).Tampa, and much of Florida, are later to the game in part because of expansion costs. Each double-decker bus costs about $750,000.Social media, namely Megabus' 207,000 Facebook followers and 20,000 Twitter followers, convinced the company it was overdue expanding throughout the Sunshine State.Santiago Corrada, president and CEO of Visit Tampa Bay, said the company's arrival gives visitors "yet another convenient and affordable way to visit our area."Christine Burdick, president of the Tampa Downtown Partnership, said Megabus will provide a convenient travel option to reach the multimodal transportation hub in downtown. "From there, (visitors) can pick up a HART bus or circulator or, in short order, rent a Coast smart bike to get around downtown."The Tampa Bay area has other express bus service options to reach various Florida cities, such as RedCoach which has scheduled service out of Tampa International Airport and USF's Tampa campus. But Megabus is trying to cement its niche as a high-amenity, low-cost option. As for amenities: its buses are equipped with free Wi-Fi, at-seat plug ins and lower-level tables suitable for traveling families.As for low-cost: It pays to be an early bird. Megabus is currently only selling seats nationwide up to Sept. 9. Whenever it opens up a new round of limited $1 fares, its social media followers are among the first to know about it.In past years, bus operators have had mixed success garnering enough traffic to be profitable. But the combination of cost-conscious travelers, pent-up demand, and a growing residential community in downtown Tampa may mean the time is ripe for companies like Megabus.Alvich points to a study this year by the Chaddick Institute for Metropolitan Development of DePaul University which indicated city-to-city express bus transportation remains the fastest-growing and most affordable mode of transportation.Alvich has high hopes, projecting more than 142,000 travelers will go through the Tampa station via Megabus in its first year alone. "We've carried 35 million people in eight years. We've seen double-digit growth every year," he said. "We're not just another bus company."