Ah, you're adding in the cost of camping (and finding the most expensive price to quote)
My self catering flat cost me far more than my season ticket.
And it's not just 'let people put a tent up on some field' - may have been once but now people expect loos, showers, a field that doesn't flood*, and that they can get vans on and off without being bogged down**,stewarding for security etc. etc.


* memories of the 80s at Whitby
** more recent memories of Bromyard