My gut feeling is that Wizzair have increased prices in the past months, trading off load factor for better yields. At least in Germany prices have increased quite substantially. They are still cheap, but it has become much more difficult to get those very very cheap tickets. How have prces developed in the UK? Same story?
I agree - I travelled from Doncaster to Katowice and back last year and paid only £30, but when I've been keeping an eye on prices this year, I haven't seen anything for less than £50 return (excluding anything they add on later).
So just because the loads have dropped at Doncaster, doesn't mean the revenue has dropped!