Anyone know any cheaper buses than greyhound?

i am looking to plan a trip from south carolina to tennessee, and i was looking for bus tickets that were kind of cheap(because of gas being so high) and all i have found is greyhound because i have never planned anything like this before so i dont really know what i am doing. so i was just wondering if anyone knew any buses or anything like that that are cheaper than greyhound(for a greyhound ticket its going to be 100 and something dollars for a one way both ways are 200 and something)i thought that i could get it a little cheaper and i have heard that i can, does anyone know anything that can help me. thanks!