And, BTW, they're forcing people that take buses and limos that park in the bus/limo lot THAT WANT TO TAILGATE to pay the $15. If you don't want to tailgate, you don't need to pay the $15. Of course, you also need to question your life as to why you're at a Bills game and NOT tailgating, but that's on you...
From the Q&A link a few pages ago.
Q: So... boil it down for me in the bus lot. If you’re coming on a bus, you now have two options?
A: If you’re not tailgating, nothing really changes from last year… you need to purchase your permit in advance. It’s still $100, but there’s no redeposit required.
The tailgating option is really dependent on the capacity/size of the vehicle. The costs really break down to $15 per-person, regardless the size of your group. Those rates can be seen at tailgateguys.com