Ticket prices are mostly set by the sites that sell the tickets. They have YEARS, like 15 or so years of data on tickets sells for a teams home games and their opponents. They know what tickets sell for with certain opponents. So as soon as niners were confirmed... bam, prices skyrocketed.
Sure Packer fans hav a large following, but do you think those living up in Wisconsin make anywhere close to what the avg worker in the Bay Area of California make? I just looked, it is 49k in Wi and 112k in Bay area, and I think that number is WAY too low IMO.
So yea, those in Ca are far more likely to have the coin to jump on a plane last minute and fly to Dallas for a playoff game.