Unfortunately you are the only one that can answer that because you know your spending habits. One thing that is always suggested is bring twice the money you would normally expect to spend.
Seeing everything goes on a sign and sail card onboard the ship it is easy to run up a higher bill than expected. Make sure you always check your receipts that you will be given even for a drink. There will be an automatic 15% tip added to each drink bill also.
You will probably buy a few pictures that can add up quickly and probably a few gifts from the ship.
The tours from the ship can run from $25 up into the hundreds of dollars per person depending on the type of tour you take.
Your best bet is figure what you can afford to spend and than keep track of how much you spend with the receipts and try to stay within your own budget.