Hi hit spacebar-choice.
Booking a cruise is like buying a car, the advertised product has a price "from" which is always the most basic on offer. For a cruise this means the 'base' price is the least attractive stateroom (cabin), on the lowest deck with no window (internal). The prices climb just like cars as the size increases and by location. The centre of the ship is always popular due to reduced movement, so they tend to have a higher price than the forward and aft locations. Add to this ocean views (window) or balcony and the price will increase.
All these price levels are set out on the various cruising web sites and as well as the cruise lines themselves. So, the cost for a cabin should not be a shock. I believe cruising is one of the best value for money holiday options.
However, there is a trap with cruising which is the very high cost for "extras". It is quite possible to have a cruise and incur no extra cost after paying for your cabin. The amount of food is amazing, and it is possible to have top quality meals breakfast, lunch and dinner even multi-course meals PLUS snack at all hours without costing another cent! Where the cruise lines catch people are if you want something to drink other than plain water. tea or coffee. If you want specialty coffee, "soda" or anything alcohol they are very, very expensive. On a cruise in March there was a bottle of "5-th leg Sauvignon Blanc" for US$57 - I could get the same wine from the local bottle shop for $13!! It is possible to get a drinks package, but to get value for money requires a huge number of drinks to be consumed every day. The trick is to watch for the daily specials for wine, you can save a lot with these.
The other area where cruise lines hit hard with cost is shore tours where the mark up is enormous! However, it is sometimes better to pay the extra and use the on-board booked tour to ensure that it is safe and guarantee getting you back on the ship before it sails! If you are comfortable with the port a lot of money can be save organising your own tours.
The issue raised about the different actual price compared to the stated price could be due to the exchange rate changing. The currency on ships depends on the home port. So a US based cruise line will have all costs in US$; when you display the cost in A$ the amount will vary by the exchange rate which the cruise line has determined applies at the time.
As for VAT, it again depends on the home port. For the US it is always added after the sale and it is usually not shown in the displayed price. This is quite disconcerting for Australians who expect the GST to be already included in the price. Canada has the same system as the US, and there can be different rates of VAT depending on the item - I have no idea how that works!
Yes, cruises can be very good value, but at the same time, once you are on board there are many temptations to spend, and spend a lot. Passengers are a trapped market, so thee is not a big choice, plus there is the psychological factor - you are there so why skimp, why not just enjoy yourself!