It's 5 pounds, that's not much at all. That will basically cover their costs and get rid of people who aren't serious about it.
They could have charged 20 pounds, or 100 pounds if they wanted too. If you can afford season tickets you can sure as hell afford 100 pounds. They obviously aren't trying to take advantage, they just want to know who's still serious.
The money they get from this will pay Gerrard's salary for a week.