Ever since the first duty-free shop opened at Shannon Airport in 1947, travellers have been trying to score bargains on local chocolate or tax-free cigarettes every time they fly. According to Duty Free World Council report, Europeans make up 31% of all duty free shoppers worldwide. Specialized shops are the major contributor to airports’ budgets across the region. While yearly increases in flight delays suggest that Europeans will have even more time for shopping, only a few flyers are aware that not every bargain is a steal.

In short, “duty-free” means that the retailer is selling goods that are exempt from certain local or national taxes. In turn, the story is able to offer lower prices than the general market. However, since 1999, shoppers on intra-EU flights can no longer benefit from tax-free prices. Passengers with destinations outside the union are the only ones that can still enjoy some big discounts.

This has been repeatedly mentioned by pro-Brexit groups: once the UK leaves the EU, Britons are likely to celebrate the return of a duty free shopping. On the flip side, it’s good news for EU shoppers as well, for a three-hour delay to or from London might soon grant them both up to €600 in flight compensation and more time to look for best duty-free deals.

When it comes to bargain hunting, there are several categories of items you would want to look at before you do anything else. According to Irish Times, savings on mid-tier alcohol brands range from 50% to 78%. The more high-end liquors are likely to be offered at the same price as in your local store. Smokers can expect up to 50% savings on tobacco, while beauty goods like perfume are sometimes almost 80% cheaper at the airport.

“Eurocontrol analysis shows that European flights delayed by up to 2 hours is set to increase seven-fold by 2040. Steadily increasing passenger traffic and the lack of ground and air professionals in 22 years is set to affect 470 thousand passengers per day. While this is terrifying news for passengers and there will be measures taken to increase airport and airline capacity, duty free shops, on the other hand, will certainly feel the upsurge. In this light, getting familiar with pros and cons of duty free shopping is a winning strategy for every traveller,” says Marius Stonkus, the CEO of flight compensation company Skycop.

But price is not the only attractive feature of duty-free products. According to DFWC report, less than a third of travellers around the world think that duty-free shops sell exclusive and unique goods. However, duty-free stores are the only places that sell 50ml and 100ml perfume bottles, some of the world’s rarest spirits in 1 liter bottles, and travel-savvy makeup.

While shopping for alcohol, beauty goods and tobacco at the airport almost guarantees a good deal, there is one category of products you should avoid – souvenirs. Retailers are aware of the fact that airport is the last place where a tourist can get some of these bits of memorabilia. Thus, shops raise the prices on T-shirts, postcards, magnets and other objects oriented at tourists. Leaving souvenir shopping for the last minute is never a good idea – best get your fridge magnets early!