BTW Ticketmaster adds on once you put the tickets in your shopping cart. ATM StubHub has less expensive seats, which isn't surprising, as the NFL Ticketmaster system only lists tickets that they have control over, they don't allow listing when someone doesn't have tickets in hand or rights to the tickets. In this particular case we haven't even had distribution to players and staff, so those can't be in the NFL Ticketmaster system, but conversely, StubHub will allow them to be listed with a future ship date. Net effect is more tickets on StubHub = lower prices.
That said, I seem to recall last year that maybe Wed or Thu before the game was the sweet spot, many people were getting tickets for $200 or so above face value for nosebleeds i.e. $800 or so for tickets in the upper corners.
I would suspect that would hold again this year, similar situation in that neither team is particularly close to the venue, so once you get past the one week mark, airplane tickets become feloniously expensive, and it's not a quick or easy drive from Seattle, and most people won't commit to the trip without having game tickets in hand... so unless there's a huge amount of interest for tickets, prices should drop as sellers get nervous.