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.

But the hottest technology item over the peak retail period, has easily been the 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 accounts for the bulk of Myer's Boxing Day sales, followed by shoes. Over at David Jones, men's shirts, towels and Lego sets are being pulled off shelves.

High-end 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 this was only a reality for those who managed to get through the retailers' doors.

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

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

In a bid to alleviate the queue of cars building outside Highpoint shopping centre, a free 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."

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

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

Boxing Day alone is 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 shops, as major retailers fight to open their online stores earliest.

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

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

Popular sites joining the Boxing Day bonanza with more than 50 per cent sales include 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, according to the Australian Bureau of Statistics.