Hotels could cost you anywhere from $25 to $150 a night depending upon your personal preferences - I typically spent about $35-40 a night for decent, but not deluxe, accommodations within a block of beach road. My best budget recommendations would either be one of the Sabai group (I'm partial to the Sabai Inn) or the Eastiny Group (Eastiny Inn or Eastiny Place are good choices).
Food could cost anywhere from $10 a day to $50 a day, depending upon your tastes.
And of course, the biggest variable of all would be for "entertainment".