Have you gone over to the VolNationTicket Forum to see what's available there? Maybe look at some gator message boards to see if there's someone who's selling there but you'd be sitting with unfriendlies.
While driving to Knoxville, you may want to keep an eye out and see if any cars have notes in their windows about tickets for sale. I used to see that when I drove up from middle Tennessee.
There were people on the street scalping at Ball State and at Pitt (which is also all electronic) so that will be an option.
Regardless where you look, it's a sellers market. Good Luck.