Haha this thread appears every year... if you're not happy with the price then don't drink it. £5 is the most I would personally pay for a pint but it's definitely around the price I would expect to pay at a sporting event because unless you do what I did last year at Huddersfield and get absolutely bolloxed, they're not going to make any money by offering it are they as the majority will only purchase 1-2 drinks maximum. It cost me an extra £30 on top of my match day ticket but it was my choice to do so.
A deal might not be a bad shout though, 3 for the price of 2 maybe something like that on bottles?