When receiving a quote, make sure that the quote INCLUDES everything. Port Charges, taxes and fees. Don't just go by the "flash" price on the front of an add. Sometimes this requires you to go through part of the online booking process. ALWAYS COMPARE THE TOTAL COST.
Other things to know is that you will also have $10 per/day per/person added to your onboard account for gratuities. This is divided among your cabin steward, waiter, asst. waiter, head waiter and maitre 'd. This totals to $70 per/person for the cruise.
You will also be required to purchase your own liquor and soda. All other beverages and almost all other food is included. There are a few specialty restaurants that have a $20 to $30 service charge.
There are true "all inclusive" or almost "all inclusive" cruises. These are the luxury lines such as Seabourn and Regent Seven Seas. These lines, while giving you a larger cabin, Regent is almost all balconies, their price is almost double or triple what you will pay for an outside cabin on a Premium line. If you book suites on a Premium line then they may be an alternative.