Where nifty gadgets including the "selfie stick", GoPro cameras and games console bundles dominated Christmas sales, on Friday buyers were after cheap big-ticket technology items.

"People want to buy presents over Christmas, but post-Christmas they buy for themselves," Dick Smith's regional director of buying Neil Merola said.

Discounted HD TVs - the 50-inch Sony and the 60-inch Panasonic - were also popular, while computers and tablets from Samsung and Laser, Google's Chromecast and Microsoft's Surface Pro 3 were snapped up by buyers.

However, the hottest technology item over the peak retail period has easily been fitness device Fitbit Flex.

"It's interesting to see when the doors of the store open where customers run to. This time it was to the TV wall and computer desks and fitness, the Fitbit particularly," Mr Merola said.

Intimate apparel and hosiery account for the bulk of Myer's Boxing Day sales, with shoes next, while at David Jones men's shirts, towels and Lego sets were being pulled off shelves.

Premium products popular with buyers included Jimmy Choo shoes, the Michael Kors tote bag, Chanel No 5 perfume and linen from Calvin Klein, Ralph Lauren and Yves Saint Laurent.

Christmas decorations were also a hit, with stock running out early.

But that was only a reality for those who managed to get through the retailer's doors.

Car parks were overflowing by mid-morning at large suburban shopping centres, as hordes of shoppers marched to their local centres from dawn.

Security was more than doubled at most centres to combat theft, while police officers were called for traffic control.

To alleviate the queue of cars building outside Highpoint shopping centre, a shuttle bus servicing surrounding suburbs was provided.

"The centre is absolutely buzzing - we've reached capacity in our car park," Highpoint manager Cara Calandra said. "This is our biggest retail day for the whole year. It is an absolutely crucial day."

Crowds gathered at David Jones, Top Shop, Zara and Mecca, Ms Calandra said.

The Australian Retailers Association tipped Victorians to out-shop all other states, with the state expected to fork out about $682 million on Friday, with New South Wales trailing at $584 million and Queensland at $374 million.

Boxing Day  nationwide was expected to generate $2.1 billion in sales - $72 million more than last year.

Shoppers fed up with the bustle of Boxing Day have been expanding beyond the bricks and mortar stores, as  large retailers fought to open their online stores earliest.

David Jones launched its online Boxing Day sale at 6pm on Christmas Eve, while Myers opened its virtual doors at midnight.

Heavy discounts on cheap stock online retail stores were also luring consumers.

Popular sites joining the Boxing Day bonanza with more than 50 per cent sales included ASOS, Boohoo.com, theicononic.com.au, and choies.com.

The National Australia Bank estimates Australians spent $16.3 billion on online retail in the 12 months to November. This is equivalent to 6.8 per cent of spending at traditional bricks and mortar retailers, Australian Bureau of Statistics show.