Purn Holiday Park are charging £50 for 2 nights based on a 4 person tent. They're usually the first to fill up though because they are closest to the beach. Dulhorn farm had tonnes of spaces left last year, its a bit further away but it was only £26 for 2 nights.
Purn is now fully booked! i tried the other day and they told me they are now full. Another place called country view is also full i managed to book a place called Mill Farm yesterday..its about a 30min drive away though most of the places in the immediate area are fully booked. Mill Farm looks great though, costing me and 4 friends £14.50 each for 2 nights. But we can use the indoor and outdoor pools and slides for free as well as other stuff on the site so if your still looking go on their website the lady on the phone yday was very helpful and i managed to book it very easily!