Back to the original post. Living in New England, I have been to Gillette a couple of times for Bills games and have not been mistreated either time while wearing Bills sweatshirts. It may have to do with the fact that we hadn't beaten them, but no one bothered me. I even met a few Bills fans along the way.
I haven't been to a home game in many years (1999), but the last time I went was with my high school aged daughter. I bought cheap seats in the upper deck and was surrounded by a bunch of drunk Canadians that wanted to talk about hockey. You are right that traveling to games is expensive and when the Bills lost to the Giants in the closing minutes, it made it seem even worse. If thins have gotten better in the intervening years, I might take another trip. For now, I'll just watch the games on DTV.