One of my best friends is a huge Wisconsin Badger fan and alum. When Barry Alvarez took them to their first Rose Bowl in forever, the demand was HUGE - and I believe tickets were going for $500 and up back then.
They even set up a big screen in the parking area so those fans who didn't get tickets could at least watch the game and be in the same vicinity as the stadium.
Considering how many Cal alum live in within, say a 2 hour flight from Burbank (closest airport to Pasadena), I've got to believe the demand would be rediculously high.
Best thing for Cal fans would be to faces someone like Wisconsin on something like their 5th trip in 7 years or something like that - because the demand on that side would be less than if it were a Big10 team who just ended a decades long drought.