There are scalpers everywhere around the stadium and it is encouraged that you don't buy above face value but I have never seen an actual cop enforce this law. You can always negotiate down but I wouldn't pay more than face value.

There are scalpers outside selling tickets and most of them are pretty nice and funny until you tell them that you arent paying that much for the tickets.

Negotiation is the key! Outside of NRG, a lot of people try and get in so they are EVERYWHERE!! I was able to go lower than what the scalper was offering. There are so many people so the lower they go the more profit they make. If not, don't even bother I say.