The seven hidden costs of air travel driving up holiday prices

Airports are notoriously expensive, but some charges are downright outrageous. Here's how airports slug travellers who don't think ahead.

1. Airport Transfers

It's a similar situation with airport transfers — booking online before the trip is significantly cheaper than booking on arrival at the destination.

You'll also find a bit of pre-holiday research may unearth some more budget-friendly options as opposed to landing at your destination and heading straight for the taxi rank.

In cities like New York, cabs are easily the most expensive option, especially from JFK airport. The website calculated a cab ride in New York cost $82 plus tolls, more than double the cost of a pre-booked private car ($27). Airport shuttles could be more than $44. The New York subway is the cheapest option, but you'll have to battle the stairs with your luggage.

On the other hand, in London, private cars are the most expensive, priced at around $126 from Heathrow to central London. Taxis will cost about $107 for the same trip, but a coach — which you can book in advance online — could be as low as $15. The Underground runs a couple of services direct to central London, and the Piccadilly line from Heathrow terminals is a cheap and cheerful option. The Heathrow Express can be booked in advance, but the price climbs the closer you get to the trip.

2. Excessive baggage fees

There are many good reasons to not overpack, but nasty excess baggage fees are the top one.

If you're a notorious overpacker, and you think you might be caught out, you should just buy yourself extra luggage in advance, for less.

It was pointed out that for an international Jetstar flight, for example, you'll pay $108 for 15kg of checked baggage at the airport and extra fees for each additional kilogram.

Some Jetstar fares includes luggage but most economy starter fares don't. So if you had just taken the plunge when you booked, you might have paid $61 for 15kg, $70 for 20kg, $88 for 25kg and $112 for 30kg — double what you'd pay for half the weight at the airport.

3. Currency exchange

If you need cash in a foreign currency, this is also something you should organise well before your trip.

Currency exchanges at airports tend to offer worse exchange rates than other locations, and they generally charge higher fees. While many of us like to hold out to see how the Australian dollar is fluctuating before striking, it rarely pays to wait until right before your trip.

"When it comes to international travel, organising our spending money is sometimes one of the last things on our mind, with many only securing their currency in the week leading up to or even just days prior to departing," Travel Money Oz general manager Scott McCullough said.

"Instead of waiting until the last minute to exchange your travel money when the exchange rate may not be in your favour, keep an eye on foreign currency movements in the months leading up to your trip using online tools like our currency rate alert so you know when it's the best time to buy — it could save you save hundreds."

Experts say currency exchanges in CBDs tend to offer more competitive rates than airports.

4. Duty free

We've been led to believe massive bargains can be found in the airport duty-free shop but actually, that's not often the case.

While there are some savings that can be made on spirits, cosmetics and some perfumes, confectionary and wine is generally more expensive at the airport than you'll find in local retailers.

A recent study found a 360g Toblerone Gold sold for $19 duty free but only $11 retail — a mark-up of 65 per cent. The study also found a 200g packet of Tim Tams Double Coat was $8 duty free and only $3.25 retail — less than half the price.

5. Food and drink

A recent news.com.au investigation into food and drink prices at Sydney Airport unearthed some shocking charges.

A good old ham and cheese croissant may cost about $5.40 or $6.50 in the real world, but in the airport, we found they were priced at up to $13.90. A pre-packaged chicken and salad sandwich cost $9.95 and a slice of banana bread cost an even more outrageous $8.60. A roast beef sandwich came with a $18.40 price tag — more expensive that a full pub meal.

And that's just the food. If you're in the mood for a pre-flight tipple, expect to pay $12.50 for a schooner of Carlton Draught on tap and $11.50 for a VB.

A bottle of Pump water made headlines a couple of years ago after a person was charged AU$9.17 at Sydney Airport, and while water isn't always sold for that much, you're unlikely to find a bottle for under AU$4.

The evil genius of expensive food and drinks at the airport is you can't bring your own through security. That's why smart travellers carb load at home and bring an empty bottle to refill at the free water stations outside the terminal bathrooms.

6. Airport parking

Last year, the ACCC Airport Monitoring Report revealed Australia's major airports were raking in eye-watering profits from their carparks.

It found Sydney, Melbourne, Brisbane and Perth airports collectively pocketed a staggering AU$280 ($303) million in 2016-17.

"It is not surprising that the airports are so profitable given that they face little competitive pressure and no price regulation," ACCC chairman Rod Sims said in a statement at the time.

Despite consumer complaints, a draft report from the Productivity Commission defended the high cost of airport parking in February, saying costs were so high because people "value the convenience" of parking close to the terminal, which drove up "locational rents".

7. Car hire

If you know you'll need to hire a car for your trip, you have no excuse for waiting to arrange it until you lob at your destination.

According to Travel Money Oz, the earlier you book your rental car, the better the prices.

"Car hire companies set their prices based on supply and demand, and in order to secure as

many rentals as possible, they provide deals to customers who book early," the company explained, adding people could save up to 15 per cent of the cost by not leaving it to the last minute.

Booking a car at the airport on the day you arrive is the most expensive option, and by then you're limited in choice. It was found a rental car for a week in London cost $50 when booked earlier online compared with $340 on arrival at the airport.