Cheapest way to get from Michigan to Florida?

ok me and my girlfriend live in separate states (i live in michigan, she lives in florida), and i want to go to FL for a week or so or something. So what is the cheapest way to get from Traverse City, MI to Tampa, FL? i dont care if it takes a few hours or a few days. there's flights, passenger trains, maybe even charter buses or whatever you call the busses. please help. thanks :)