Ive only bought a few times from scalpers over the years, and from my personal experience, the closer it gets to game time, the cheaper you can get tickets. If you only need one, you can get it pretty cheap, I wouldn't pay more than $50 for a single ticket. If you need a pair, they will probably start the morning off tomorrow asking $250-$300 for the pair, no joke, but if you "shop around" you can do better than that. Also, make them an offer, usually for early games like tomorrow, they tend to wanna get rid of the handful of tickets they have as quickly as possible, and a profit is a profit, but remember, for most seats, ticket price was $80 each, so $100 per ticket is probably reasonable.
The best advice I can give you, look for someone that doesn't have a handful, or a scalper, try to find the dude that has two extra because a friend couldn't make it or something, they usually just wanna get their money back.