Not just there - even cutting out the clubs the whole thing can be crazily expensive compared to other places.
Last week in Ibiza - 3 nights, flights, car, hotel (Gran Sol no sea view) and a boat 1 day with keenly priced meals and some activities - £1,200. NO CLUBS
Zakynthos - 3 nights, flights, car, 600sq ft Apartment with massive private living balcony and 180 degree views of mountains and sea, boat 1 day (smaller) with tourist priced meals and some activities - about £550. I'll up it by £200 or so for the boat spec differential but still about £450 less.