If you’ve ever found yourself carting home a giant box of Toblerone, and your liquor cabinet is filled with funny shaped bottles from around the world, you may be diagnosed as a Duty Free Addict.

Don’t worry, you’re not alone. It’s a perfectly common and understandable condition: airport duty free shops like to get you at your most vulnerable state…you’re exhausted, about to face a long international flight, your wallet is stuffed with leftover currency, and hey, you can’t go into the office tomorrow empty handed.

Besides, that diamond encrusted Dior watch is something you’ve always wanted… you just didn’t know it until now.

Whether you suffer from the symptoms of duty free addiction or not, here’s a basic rundown of what “duty free” really means. A duty is the customs tax paid to import something into the country, yet airport duty free shops are exempt (since the goods are only sold to people leaving the country from airports, seaports or borders, they aren’t completely “imported” into the country; thus, the shop doesn’t have to pay a customs tax). The idea is that these savings get passed onto the buyer.

Just like grocery stores display candy at the checkout line, duty free shops are located in airports just before you check out of the country for good. They’re usually brightly lighted and bursting with tempting goods that trigger the impulse buyer in you.

In fact, a study commissioned by Halifax Travel Insurance shows that British shoppers have spent approximately 4 billion British pounds (GBP)(about $7.5 billion) in the past five years on unplanned purchases at airports - 817 million pounds (about $1.7 billion) of which was spent to use up left-over local currency. That’s why you may find yourself lugging home a ten-pack carton of Marlboros for $15… even if you don’t smoke. Which leads us to the question: when you buy duty free, are you really getting a deal? Here we look into duty free shopping to find out when it’s worth it — and when it’s not.

The top five cities with the most duty free sales are London, Singapore, Amsterdam, Paris and Dubai. Logically speaking, you should find significant savings when you shop duty free versus places where the items are taxed, i.e. within the cities you’re traveling, at home in the U.S., or even online.

However, keep in mind that these prices aren’t standardized; in fact, there is a website called The Duty-Free Price Guide which now makes it easier by comparing duty free prices between airports and airlines. For example, a 50 ml bottle of Calvin Klein Eternity Eau de Toilette spray can cost $32 on Continental Airlines and $44 in the Berlin Airport.

Still, that’s a far better deal than a bottle of the same stuff in Harrods in London, which will cost you about $74 (40 GBP). A liter of Chivas Regal 12-year-old whiskey will cost you about $26 in the Singapore Airport Changi. Compare this to shopping at home, where it costs about $46 in an American liquor store, and $36.99 at the discount liquor website www.shopperswines.com.

Another instance in which duty free shops can pay off is that you may have first access to certain products. An increasing number of companies are creating items exclusively for duty free shops before rolling them out to the general market.

Italian celebrity jockey Frankie Dettori did just this with his men’s fragrance line, Dettori, which was only available at Heathrow’s World Duty Free store in September 2005 before it hit the domestic market. Cadbury did the same with a particular praline tower pack of 29 individually wrapped chocolates, which was only available on British Airways during the holiday season, and became widely available as of January 2006.

In some cases, however, the airport or airline’s duty free shop isn’t going to offer you much savings at all… because the city doesn’t have any sales taxes! Here are just a few cities where you may find better deals before you hit the airport, when you have more flexibility and time for price and brand comparisons.

HONG KONG

Hong Kong doesn’t impose sales tax or custom duty on any goods except for tobacco and alcohol. The island is such a shopper’s paradise that its tourism board actually began sponsoring an official “Summer Shopping Festival” three years ago. This summer, the festival runs from June through August (2007), when shops offer even deeper discounts and extended store hours to entice visitors during otherwise slow travel months. There’s also a slew of entertainment, including the Aqua Fantasia spectacle, featuring a high-tech visual display set against a “water curtain” of Victoria Harbour, plus pyrotechnic shows on Saturdays.

In Hong Kong, you can find almost anything you can imagine, including antiques, furniture, ceramics and porcelain, jewelry and cosmetics. Just keep in mind that this is also a mecca for knockoffs and frauds, so if you’re looking for the real deal, stick with the name-brand stores or go by personal recommendations. And take note: the government has recently made moves to introduce a goods and sales tax, which will take at least three to five years to implement, but has shoppers and business owners concerned for Hong Kong’s future as a major shopping destination. For more information, visit www.discoverhongkong.com

ANDORRA

It may be hard to find on a map, but the tiny principality of Andorra is a virtual drive-through duty free market between France and Spain. It’s estimated that about nine million travelers visit Andorra each year, primarily because of the duty free shopping and its mountain resorts. While Andorra’s numerous mini-malls (ambiance is not really a factor here) offer lower-priced electronics, clothing and cosmetics, one of the more popular purchases here is…whiskey. Cava Benito Whiskey (Av. Carlemany 82, Escalades, www.cavabenitowhisky.com), for example, offers about 600 different whiskeys.

DUBAI

In Dubai is the biannual Shopping Festival, which usually takes place June through September, and again from December through February (this year’s festival ended on February 2). During the festival, shoppers can visit more than 40 malls, boutiques, souqs (open-air markets), and street vendors for discounted items, while experiencing concerts, dances, art exhibitions and promotional raffles (you might actually win a Rolls Royce). For more information, visit www.mydsf.com

For a really over-the-top duty free experience in the Dubai Airport, there is the Dubai Duty Free shopping concourse. Established in 1983, the world-famous center offers 5,400 square meters of shopping, with electronics, cosmetics, liquor, jewelry, clothing, sports equipment and nearly anything else you can think of. Over the years, Dubai Duty Free has garnered numerous awards, including Airport Retailer of the Year at the Tax-Free World Exhibition and Middle East Travel Retailer of the Year. For more information, visit www.dubaidutyfree.com

You could do some shopping with your galpals with Women’s Travel Clubs. Or just check out the rest of our Shopping section.