I think that there are several reasons for that:
1- Buffalo is a very small market
2- A lot of secondary market buyers live outside of the Buffalo area
3- The problem with NFL playoffs is that any game is official (opponents, date and time) only 5-6 days before the game so most of the potential buyers, who live outside of the Buffalo area have very little time to organize their group including hotel and transportation.
4- Not many are excited about the Broncos vs Bills matchup. We expect an easy win and we are already looking forward to the Ravens - Bills matchup next week.
5- It's cold in Orchard Park in January and it's not an indoor stadium.
6- Canadians are a big chunk of the secondary market buyers and we are totally killed by the 47-48 per cent current exchange rate that our credit card will charge us on all of our expenses going to the game (Tickets, hotel, parking, food drinks, gas, tolls, etc.)