Prices vary on the cost to go to the Bahamas. You left out a lot of information. Like how long to you want to go for and are you going alone. Where is your starting point and do you need a rental car and a hotel room.
Now that is really vague question, as the cost to go to Bahamas depends on many factors like, your starting point (as airfare differs), your habits (if you are a party lover and like to spend more then it will cost you a lot), etc..