Bargain behemoth Costco opens ‘huge’ new Sydney warehouse

Members-only shopping warehouse Costco is being rolled out in Sydney’s Marsden Park.

The city’s third Costco, and the ninth to open across the nation, comes as the retailer’s market share is projected to rise from 2.3 to 2.5 percent.

"Gas prices, electricity prices are rising. Consumers’ incomes are falling and we're starting to see that consumers are starting to more go towards the low cost supermarkets such as Aldi and Costco,” Nathan Cloutman from IBISWorld told 9NEWS.

“It's good for competition. Competition makes us all a bit sharper and the consumer wins. "

The next 14,000-square-foot warehouse on Langford Drive will open next Wednesday, offering members a slashed prices on shopping staples like fuel, fruit, eggs, bread and milk.

Costco also has some unique items available for purchase, including a 10 kilogram block of chocolate and a $100,000 diamond engagement ring.

“We have got a 14,000-square-foot warehouse and we’ve got about $20 million worth of inventory today,” Costco manager Patrick Noone told 9NEWS.

"It's huge, it's a big building.”

Costco memberships are $55 per annum for businesses, and $60 for non-business members.