I think that varies. You are much more likely to see a Steelers or Packers fan at a Dolphins or Jaguars game than a Dolphins or Jaguars fan at Heinz or Lambou.
As I'm sure you know the Steelers' and Packers' fans have always traveled well. A big part is also that they usually have good teams so they have a high number of season ticket holders that show up to games, hence it's expensive for opposing fans to buy tickets for those games, if they are available at all.
On the other hand, after decades of being bad it's cheap to get really good seats for a Bills game. My brother has season tickets for the Bills down low near the field and can't even get face value if he tries to sell them.