Is it worth joining Costco? We reveal how its prices compare to supermarkets

COSTCO shoppers rave about the bargains they find and willingly pay £30 a year, simply for the pleasure of shopping there.

But with 28 locations in the UK, do these wholesale warehouses really deliver the deals? And is it worth forking out for an annual membership to stock up your storage cupboard with bulk-buy bargains?

The majority of Costco’s customers are traders but a third of shoppers are buying for themselves.

It's a pretty exclusive club and you must have - or be retired from - a certain type of job to get accepted.

Qualifying jobs include public-sector workers - such as the NHS, education, emergency services, local government - or a qualified professional such as an architect, solicitor, engineer or accountant.

If you don’t fit the criteria, you can still shop at Costco, but only online – and you'll be charged a 5 per cent surcharge unless you pay £15 for an online membership.

A “full warehouse” membership costs £24 a year for traders and £30 for members of the public. The membership includes a complimentary card for a spouse or partner.

An “executive membership”, which pays 2 per cent cashback on most purchases, costs £60 for a trader, or £66 for ordinary shoppers.

Bear in mind that all membership cards have your photo for identification so you can’t hand it over to friends and family - but you can take up to two guests with you on each shopping trip.

How does Costco stack up against the competition?

Before you set foot on the shop floor, it is vital that you remember that the prices on the shelf don't include VAT, so deals may appear much better than they really are.

Look just below the advertised price (in much smaller print obviously) for the full amount you will be expected to pay at the check out.

To see how the wholesaler stacked up against the competition, The Sun Online looked at the deals at Costco (inclusive of VAT) and compared them with products on offer at the main supermarkets and Amazon.co.uk – including any offers available in our calculations.

As anticipated, Costco prices are cheaper, but perhaps not by as much as you would expect – especially once you factor in the cost of the annual membership.

There are also some occasions where you would do better buying on the high street, proving that shoppers must do their sums carefully when shopping at the discount warehouse.

Costco came up trumps on laundry detergent offering a huge 130-wash box of Fairy Non-Bio Washing Powder for just £18.69.

A quick look at Tesco and Sainsbury's shows that the same amount of washing powder would cost a third more – both supermarkets sell 65-wash boxes for £12. To take home the same quantity (130 washes), you would need to fork out £24.

What’s more, Amazon.co.uk is even dearer, with a 130-wash box priced at priced at £24.45, including free delivery.

Similarly, Pampers Baby-Dry Nappies Size 3, 136 Giga Pack, is £10.79 at Costco (or just 8p per nappy), while Tesco sells a pack of 100 nappies for £14 - or 14p per nappy.

A 20-pack of Duracell Plus Power AA Batteries is selling for £9.90 this week at Costco, compared to £13 at Sainsbury's and £12 at Asda.

If it's toothpaste you are after, its worth filling up your trolley with Oral B 3D White Luxe Perfection Toothpaste at Costco as it is nearly a third cheaper there than at its competitors, with four 75ml tubes priced at £8.83.

If you were to buy the same toothpaste at Tesco and Asda, the best price you can find is one tube for £3 when on offer.

But don’t let yourself get carried away - bigger isn’t always better, especially when you'll not use all the product before it expires.

When that happens, it is just false economy. Keep this in mind when buying fresh produce or condiments such as mayonnaise and ketchup.

What’s more, sometimes the savings aren’t worth sacrificing storage space in your home.

Just take a look at the Fairy All In One Original Dishwasher Tablets, for instance.

Shoppers at the wholesaler will find 200 dishwasher tabs for £29.89 (or 15p per tab), but a quick look at Tesco and you can get 84 tablets for just £12 (or 14p per tab) without having to find somewhere to put the larger quantity.

A tub of Cadbury Drinking Chocolate costs the same at Costco as it does at Tesco, Sainsbury's, Asda and Amazon, and at Costco you'll need to buy a minimum of two tubs.

Bear in mind that the mountains of books and toys in the centre aisles are there to tempt you to buy on impulse.

A quick look on your smartphone on the shop floor and you are likely to find the same item for a fraction of the cost.

Take the Maeve Binchy 5 Book Shrinkwrap Set selling at Costco for £10.99. Buy from the The Book People and you will get ten books written by the author for just £9.99.

We pay for your stories! Do you have a story for The Sun Online Money team? Email us at money@the-sun.co.uk or call 0207 78 24516