I know I've seen -400. And I *think* I've seen -500 before...in fact, I think it was Pens @ Flyers last year...after the Pens traded all their good players.
But -700 is crazy...I guess the books simply didn't want people taking the "free" money on the Flyers. So they posted a HUGE line to scare people away from the Flyers.
Go figure, Pens were up 1-0...but it didn't take long for the Flyers to make it 1-1.