Costco's secret tricks to get you to buy more

Costco has made its reputation on the basis it's the best place to grab a bargain and save cash – and it can be, if you shop carefully.

Like most retailers, however, Costco uses several tricks to entice shoppers to buy more than they'd planned to, and they are psychological in nature.

It all begins when you sign up as a member, according to British consumer journalist Harry Wallop.

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He tells Channel 5's Costco: Is It Really Worth It? program the membership is designed to make customers feel like they are part of an "exclusive club" so it feels like they are "getting access to exclusive bargains to own branded goods that you can't get anywhere else".

Wallop explains while buying in bulk can give you the best bang for your buck, that isn't always the case.

"The real trick with Costco is you have to go in with, frankly, a calculator and internet access and just check prices, because it really does depend," he says.

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"Some things are fantastic value, and some things aren't good value at all."

Then there is the layout at Costco stores, using the same trick used by other grocery retailers by placing essential items like bread, milk and toilet paper in the back, forcing customers to walk past displays designed to entice them to purchase.

It's also why signage isn't as clear as it could be.

"The layout is quite chaotic, so often as a member you're having to go on a voyage of discovery every time," Miya Knights, a retail expert and author, explains.

"It's absolutely their aim for you to walk out with something you didn't intend to buy in the first place."

Costco opened its first store in Australia in Melbourne's Docklands in 2009 and was an instant hit. There are now 13 stores across the country with plans for more locations.