The Camping and Caravanning Club?
If yes,
this is the website link.Site prices vary depending on how good the site is, ie a combination of facilities and location,
e.g. as a member backpacker I would pay £5.60 to £6.50 per night camping at Dunbar from low to high season in April 2011
(a non-member backpacker pays £7.15 to £8.45)
Generally going as a member backpacker (or cyclist) is £1 to £2 cheaper per night.
With annual membership at £37 for you and your partner it will take about 9 nights camping in high season to break even on a simple outlay basis.
There are other benefits as a member, read all about it on the website if you are thinking about it...
e.g. you can book in advance on-line, whereas it is by telephone only in advance for a non-member.
I hope this helps.