It was free when I used to do it last year. I usually rode the bus over to the stadium and then walked back. Getting out isn't bad because you can get on Alcoa highway to get on the interstate right there.
I commuted as a student as well, and for basketball games, my friends and I always parked in the Lake Avenue garage. The street/garage is below the parking lot behind Reese Hall. Mainly non-commuters park in that garage, but it is easy to find a spot on the third through sixth floors and blend in with the commuter parking tags. If you have your non-commuter parking tag you can park on the 1st and 2nd floor without risking a ticket. Those floors are for faculty/non-commuters. No money involved.
After that, it's just a 5-10 minute walk to TBA. After the game, you don't have to deal with Neyland traffic, and it's easy access to Cumberland or Vol Blvd.
Park at Lake Ave garage if you have a commuter pass and just say you are going to study for finals if they give you any crap there, its like a 10 min walk through campus but its easy to get out