2 nights in Male/Hulhulmale would cost you around 5k per person including food and sightseeing on twin sharing basis. 1 night on private island would cost 5k-30k per night depends on the resort and the room amenities.
It depends on the festive season ie Eid as local people visit various resorts during that time . if you are from south india it will not cost much from thr ..book your tckts prior 2 to 3 months . thr are many resorts with various offers .its better you go in group so you can share prices if you take a room in resort ..nrmly it costs 3 to 400 usd fr a night .