Budgeting for a Cruise . . . Most people soon discover that the advertised price for a cruise is not exactly the end of spending on that cruise. I have not included some obvious things such as film, medical supplies, etc.
Some ships have self-service laundries.
Sample prices, from RCI, are linked to. You don't have to buy any, of course. Shore Excursions depending on where you are cruising and what you want to do this could range from nothing to several hundred dollars or more. Drinks, Meals if you won't be back to the ship for lunch, etc. There are several ways you can save money, if you are so inclined.