We are paying £19 per night for a week in Newquay for two adults, two teenagers and a 3 year old later this month, that's with entertainment, excellent facilities inc swimming pool, and includes an EHU...
Cheapest we have paid is £5 a night for a CC&C certificated site in Derbyshire (a field with a loo), the most expensive was about £27 a night in Cornwall - site with bar, indoor pool, entertainment, shop, amusement arcades.
Both were great for our particular needs at the time (although personally I prefer the field with loo).
The prices per night on campsites these days are increasing rapidly. With this credit crunch in full swing now, more and more people are turning to camping as apposed to going abroad. It reported on this on the news this morning.
Soon, sitting under canvas in the rain will cost you the same as lazing in the sun abroad! Perfect example of this as a post in this thread says they are paying £39 a night!! That adds up to £546!!! Thats shocking!! You could go abroad for not much more than that!!