Cruise control: 'Carnival Freedom' / Getty
The man who pays his way

Travel experiences may be priceless, but the only way to assess the value of a trip is to compare it with other options and calculate whether or not you can afford it is by knowing the price.

Since National Cruise Week begins today, consider the western Caribbean cruise aboard Carnival Freedom, due to set sail from Fort Lauderdale on 15 November. The timing is ideal: the storms should have subsided, the islands will be fresh and the crowds thin in this lowest of all seasons. She will call at a cultural compendium of alluring islands, including Antigua, Puerto Rico and the Franco/Dutch island of St-Martin/Sint Maarten (where, were I a passenger, I would make straight for the airport to watch the jets scrape the parasols as they come in to land). All yours for $419 (£262), according to the cruise line's US website.

If you have only $420-worth of headroom remaining on your credit card, though, forget it. You have no prospect of watching the sun set as the Florida shore retreats. Americans are accustomed to all manner of extras being added to quoted prices, and in this case the per-person cost rises by $224 in "taxes, fees and port expenses". It's the equivalent of £350 – leaving aside tipping, of which more in a moment.

You need to pay for flights on top. Given that Norwegian has the only link to Fort Lauderdale it make sense to use that airline's service from Gatwick. The appropriate departures are currently priced at £450. The flight timing means you are obliged to spend 24 hours in Fort Lauderdale before and after the cruise – so you can follow our recent 48 Hours guide to this pretty and cultured city ( in two halves at the beginning and end of your holiday. The only downside: about £100 a night for a double room. The per-person total: £900.

What could be better than that? Well, the same deal, professionally packaged by the specialist UK agent, Cruise Nation, which during the week was selling the whole deal for just £699. Except that you can't buy it for that price.

Many firms send tempting bargains to the travel desk here with a view to disposing of distressed inventory. Call us cynics, but we test deals before publishing them. When I phoned Cruise Nation to check it out, it turned out that the real cost is £723 per person, because a £24 "booking fee" is added to the advertised price.

We don't do that here

The British principle is that if a holiday is advertised at a particular price, and you can jump through all the hoops (departing mid-November in a party of two, flying with hand baggage only, paying with a debit card) you must be able to buy it for that amount. Travel firms are, of course, perfectly able to offer all manner of extras, but unavoidable and pre-payable fees must be wrapped into the advertised price.

Price-based travel firms want to advertise the cheapest deals they can. But Cruise Nation's behaviour is baffling. The Code of Advertising Practice insists: "Quoted prices must include non-optional taxes, duties, fees and charges that apply to all or most buyers." And the firm is a member of Abta, the travel association, whose code of conduct says quoted prices "must include all non-optional extras of a fixed amount".

I sought an explanation from Cruise Nation's chief executive, Phil Evans, about why the company appears happy to break the rules. But the statement I received merely repeats the small print on the website about what the booking fee is said to cover: "The administration cost of providing our booking and customer support service, which is run by our team of travel experts in our Swansea office, as well as providing our customers with Atol protection, supplier failure cover and cruise protection cover."

Which is not the point: the booking fee is supposed to be included in quoted prices.

Mr Evans's statement ends by saying: "We're confident that Cruise Nation offers the best value for money in the cruise industry and nobody beats our prices." If that is the case, it makes sense to tell prospective customers the real cost; a 10-night trip to Florida and the Caribbean for £723 is still an excellent deal, with the cruise element much cheaper than you would find were you to book direct.

Top tips on gratuities

When American passengers learn how little the Brits paid, as surely they will, they may be furious. So why doesn't Carnival just leave cabins empty rather than flog off "distressed inventory" cheap in Europe, and risk upsetting their core market? Because the business model for the cruise industry is based on 100 per cent occupancy. Passengers spend money on board, in the shops, casinos and bars. Many take excursions, for which the cruise line earns a fat commission. And then there's tipping.

Just as Americans tolerate a range of unavoidable extras being tacked on to the cost of their vacation, they accept that gratuities are ingrained in service industries. The most obvious example is a restaurant bill: 15 per cent is the minimum you can tip. Some bills helpfully arrive with calculations of 15, 20 and 25 per cent tips already made.

On cruise ships, you are instructed how much is expected: on that eight-night Carnival cruise, $12 per person per night, meaning an extra £60 each. It is added automatically to the on-board account, but will be removed if you insist – though this requires a visit to the Guest Services Desk, where you are expected to say how staff have failed to exceed your expectations. That is not a conversation many of us would enjoy, so we pay up and the crew get their tips.