Without renting a car, or taking a very-expensive taxi for the 70-mile-plus drive, an alternative is the Greyhound bus. The downtown Tampa station is at 610 East Polk Street, and you can make your way there, using the Hillsborough Area Regional Transit bus that leaveleaves from the TIA Terminal.
Another option is the Super Shuttle (a personal preference among airport shuttles): a rough estimate of the cost is under $100; your specific destination would affect that. You can book online, as well as pay in advance, for both the ride and gratuity. While more than the bus, it takes you door-to-door, expeditiously, and without any other costs for ground transfers.
Rome2Rio.com is a useful tool for this kind of search., as this was, and you can refer to it for detailed bus numbers, routes, and times.