Here is the example of all obligatory and optional costs for one of the sailing yachts and catamarans:

SAILING YACHT / CATAMARAN / MOTOR BOATS: 3,735.00 €
Standard charter pack: 170.00 € (OBLIGATORY)
Tourist tax: 1.30 € per person per day (OBLIGATORY)
Skipper: 1,050.00 € (OPTIONAL)
Hostess: 910.00 € (OPTIONAL)

And here are some estimates expenses:

Fuel est.: 250 – 350 €
Mooring fees est.: 200 – 400 € Presuming that most of the nights will be on the anchor or mooring buoy. Some people will go entire week with only 150 € spent on mooring fees. It also depends on the weather. It is safer to be in marina if there is a storm.
Food: 450 €+ (provisions for boat + skipper) Please note that this does not include dinners in restaurants. Meals in restaurants are 15 € for pizza and soft drinks, while full meals are 25-35 € per person.

VAT is included in all the prices.