Prices of a CL - Too expensive at £23+ per

Was searching for a new CL to try near to us and came across York Marina.   They are charging £21+ per night, not mention extras such as awnings.  I cannot for the life of me understand why someone would a) charge that much for a CL or b) why anyone would PAY that much for a CL!     For larger units it's £27+ per night.    What are members thoughts - far too expensive for me, might as well use a commercial or club site for that extortionate price.    

http://www.caravanclub.co.uk/planning-your-holiday/uk-holiday-planning/uk-site-search-and-book/new-certificated-locations/site-detail/?Id=561650&dateAdded=01%2f01%2f2012

or

http://www.yorkmarina.co.uk/caravan-site-york

Interested in members views on this one - are they pricing themselves out of the market?