Open a savings account that is connected to your checking account, that is specifically for the Bahamas trip. Deposit $5, $20, whatever you can afford. It's easiest to deposit at the beginning of pay periods, rather the end.
try to give up 1 thing you spend money on now, such as coffee at Starbuck's lottery tickets even eating out and pay for everything you can with cash, save the coins you receive in change put your coins, other$ you saved that day in a shoebox, at the end of the week take$ 10 from your pay check as well as the other monies you saved and deposit into a christmas club savings account(so you cannot access it) when december rolls around you may just be very surprised how much this has added up ...also , for a jump start you could give the account a good infusion of cash by taking 5% of your tax refund and depositing that and finaly,bring any unwanted nice pieces of clothing shoes ect to a consignment shop they will pay you everytime they sell one
When going out eat order from the right side $$ of the menu. Skip desserts and drinks. Make note of the amount and add it to your savings, because you SAVED the money did you not. You are saving short term gratification for a long term desire.