What a carry on
How much would you pay for a designer handbag? £300? £600? £11,000? Somehow the goalposts have shifted so that no-one bats an eye at a bag that costs as much as a weekend in New York, but the fact is, the cult of the 'It Bag' means what you choose to carry is big business. Where 5-10 years ago you'd think long and hard before investing £300 in something as frivolous as a handbag, now the average price of an 'It Bag' is more like £600. And the £11,000 bag? That's the so-exclusive-it-doesn't-even-see-the-salesfloor limited edition Fendi B from Harrods' By Appointment only personal shopping service.

Because it's worth it
Why are we prepared to pay so much? Nicola Sugden, handbag buyer for House of Fraser explains, "A great handbag works with many outfits so the price per wear starts to look very affordable. Plus, you don't need to worry about squeezing into it, it looks fabulous on every size." The tipping point of the It Bag phenomenon dates back to Mulberry's Giselle, a canny collaboration with London designer Luella Bartley whose cool credentials lent instant cachet to the brand. As Sugden puts it, the combination of luxury label, stylish design and media frenzy adds up to a must-have bag that will be obtained at any price. The high cost in itself defines a strong level of aspiration.

She's gotta have it
There's no question women have an emotional attachment to fashion - we honestly believe a new bag might change our life. The latest clutch of roomy, pocket-laden bags are so functional it's easy to feel that they really do make life easier (mmm, and they look so gorgeous too). If you want the bag badly enough you'll convince yourself it's worth it. And don't disregard the power of the media. However immune we think we are, it's easy to get sucked into must-have mentality with every new label that hits the stores. Take Stella McCartney's recently unveiled bag range. It's not even leather yet these high fashion tote bags are certain to sell out despite their £700 price tags. Or look at the impact It bags have on the stars - Nicole absolutely adores the Balenciaga Lariat bag, confessing that she has it in five colours, whilst Alex Curran prompted a cacophony of complaints to the buyers at Harvey Nichols from the WAGs in Baden-Baden when she was the first to be photographed with the latest £2,400 Chloé Python tote.

Buy it now!
So what should you look for if you fancy an It Bag but are scared of the commitment?

Go for a roomy size like a Fendi Spy. It's more practical so you'll use it more.

Invest in a style that's been around forever. A Birkin by Hermes ( if you can get your hands on one), or the Chanel 2.55/ Classic is beyond fashion and you can even resell at a later stage should you want to release the equity.

Choose a neutral colour for the same sensible reasons as above. Neutrals go with everything and don't date like bright pinks or greens.