I went two years ago and there was a good crowd. I got my tickets on Ticketmaster. I have seen USC tickets on groupon when they’re not doing well and they’re just trying to sell tickets. If SC is undefeated heading into the game, you can possibly expect a crowd. If not, you might be able to score some cheap tickets close to game day.
There are fewer seats for football at the Coliseum than there were a few years ago. There were too many for the demand. With improvements ticket prices have gone up a lot. Given the Utes have been good, they are drawing more interest in SoCal. If the Helton lead Trojans look bad, expect demand to plummet.
I caution you to not get tickets through the U by where the band sits. The coliseum is huge and we sat at like the negative 40 yard line so far behind the end zone. This was about 6 years back. Take it for what it’s worth, don’t be outside the end zone lines.