No retail experience encapsulates the journey from hope to disappointment/guilt quite like an airline seat sale.

Consumers, lured by the promise of €1 or half-price flights onto Ryanair.com and Aerlingus. com, keep their credit cards warm in their hands in anticipation of entering the 16-digit number in exchange for those heavily advertised bargains.

Minutes later, website traffic permitting, they often find that the tens of thousands of special offer flights have already disappeared, and in any case only seem to be available one-way, at night, mid-week or all three.

Consumers are forced to leave their credit cards to cool off back in their wallets or take a hit for a sum that's a little higher than planned.

The table opposite shows that Ryanair, a so-called low-cost, no-frills airline, beats Aer Lingus on price on most of the dates surveyed.

Flight costs, which include all taxes, fees and charges, were calculated using Ryanair.com and Aerlingus.com on November 5th, 2003. This includes "handling fees", which are €6 per transaction at Ryanair and €4 per ticket at Aer Lingus.

All flights depart from Dublin in the morning and arrive back in the evening, so as to maximise potential sightseeing time on the hypothetical city breaks.

Flights booked at short notice tend to be cheaper on Aer Lingus than on Ryanair, reflecting recent research by Davy Stockbrokers.

Aer Lingus appears to offer a more constant fare and thus moves from being overpriced to underpriced relative to the competition as the departure date nears, Davy noted. In other words, booking Ryanair flights at the last minute is not a good strategy for price-conscious travellers.

Although complaints are not always upheld, the Advertising Standards Authority of Ireland (ASAI) regularly handles cases where consumers say they found it impossible to find the "free" or discounted flights advertised.

In a case earlier this year, Aer Lingus objected to Ryanair advertising "free flights from Ireland" with a footnote stating that taxes and charges were payable. Aer Lingus said the amounts of taxes and charges should have been shown and that the term "free flights" was misleading.

Ryanair argued that Government taxes and airport charges are imposed by third parties. However, the ASAI upheld the complaint as its rules state that products can only be described as "free" if the consumer pays no more than postage, delivery or collection costs.

The ASAI code says that prices quoted should normally include VAT and other taxes, duties or inescapable costs to the consumer. Its aim is to ensure that inescapable costs that arise in the purchase of advertised goods or services are presented to the consumer as part of the total price.

However, while the incidence of "free" flight promotions seems to have dropped, it is the cost of the cheapest flight by itself that still features in the website headlines, not the total cost consumers must pay.

In most instances, the flights are advertised on the basis of their each-way cost but are sold on a return basis.

At the time of booking flights for this article, Ryanair and Aer Lingus were running special flight offers.

Ryanair was selling €1 flights on some routes. On the dates selected and at the time of booking, these €1 specials were available to book one-way only on flights to Bristol and London during December.

Aer Lingus was offering a 50 per cent discount for travel in November and December. On closer inspection, the discounts ranged from 30-50 per cent with the largest reductions applying to mid-week travel, Monday to Thursday.

Flights from Dublin to Heathrow were on sale from €14. In the booking exercise, these €14 flights were available to select destinations one-way only for a mid-week break in December and a four-night New Year stopover.

Flights to Edinburgh on sale from €17 were available to book both ways for the mid-week December break.

Flights to Brussels in November and December were available to book for €27 - the lowest price - one-way only.

According to the Aer Lingus website, flights were available to Paris for €24. But either none at this price was left at the time of booking or none was scheduled for the dates selected.

The most expensive flights for both airlines were those booked three months in advance for romantic breaks to Paris for a Valentine's Day weekend in February 2004.

The cost of a one-night mid-week stopover was also considered.

At Ryanair, flight costs for one-night stopovers were the same as those for two-night stopovers. However, Aer Lingus bumps its prices up on one-night stays in certain British destinations even when customers appear to be travelling on the same flights.

For example, the cost of flights departing Dublin on December 9th and departing London Heathrow two days later was found to be €92.94.

But if the customer wanted to stay in London for just one night, the cost more than doubled to almost €195.

While Aer Lingus was found to be more expensive than its budget airline rival, it offers a substantially different in-flight service, which includes meals and pre-assigned seats.

Its passenger aftercare standards are also higher: Ryanair does not provide accommodation in the event of delayed or cancelled flights, which Aer Lingus will do in some circumstances.

Crucially, on some routes Aer Lingus flies to airports that are closer to the centre of the cities, thus significantly reducing overall travel times.

The table compares prices for Aer Lingus flights to Heathrow and Ryanair flights to Stansted. Stansted is approximately a 40-minute journey by train to London city centre, compared with a 15-minute journey from Heathrow to London's Paddington station.

On the continent, the differences in journey times are equally dramatic.

For example, Aer Lingus's destination airport on its Paris route is Charles de Gaulle, while Ryanair flies to Beauvais. Charles de Gaulle is just 23 km from the city centre with a journey time of about 40 minutes. However, Beauvais is located 72 km north-west of Paris with a journey time of 60-90 minutes.

A coach service tied to Ryanair's schedule departs from Paris two hours and 45 minutes before the departure of each flight.

Similarly, on its Brussels route Ryanair flies to Charleroi airport, which is 45 km and approximately an hour away from Brussels, with coach transfers departing two hours and 30 minutes before flights take off.

Aer Lingus flies to Zaventem, which is 13 km and 30 minutes from the city centre.

At both Beauvais and Charleroi, Ryanair passengers can buy tickets for coach transfers to the centre of Paris and Brussels for €10 each way. This seems relatively inexpensive given the distance and means Ryanair is still cheaper on these routes.

However, it is the inconvenience of the added journey time that may deter some travellers embarking on short breaks from using the Ryanair service on these routes.