How much should Coldplay pay to play the Super Bowl 50 halftime show?

Last year, the NFL asked performers to start paying to play the Super Bowl halftime show. It was immediately rejected, but there was an irresistible hypothetical question there: What if the NFL was right? The halftime show reaches well over 100 million viewers, and each year, the performer sees massive financial gains as a result. What if they should pay? And if so, how much? Here's a hypothetical analysis of how much Coldplay should pay if they had to, based on all available statistics on viewership numbers, historical album and ticket sales bumps, airtime costs, etc. http://fir.mx/1N3aG5O