As I understand it, most bowl game tickets are

Pretty easy to come by. I wasn't able to make it to the Fiesta Bowl for our last national championship (somewhat foolishly in hindsight, I figured there would be others in the near future), and I lived in Jacksonville at the time. I wound up going to the Gator Bowl instead, in what was Vince Dooley's last game as Georgia head coach (vs. Michigan State). Fun fact for that game: New Year's Day fell on a Sunday that year, and the Gator Bowl was the only bowl game to play on Sunday.

Anyway, a bunch of us walked right up to the gate and got tickets for the game. Tickets cost $10 IIRC (it was over 30 years ago, after all).