Online shoppers will have the chance to bag some bargains when Click Frenzy Mayhem launches on Tuesday night, but an expert is warning that many buyers will be disappointed thanks to the use of a common marketing trick.

The 24-hour online shopping event starts at 7pm on Tuesday and promises a “virtual door-busting stampede across cyberspace”, with purported discounts of up to 99 per cent on electronics, fashion and travel.

If that sounds too good to be true, it probably is. Here’s the catch.

One expert says the organisers are using an age-old sales tactic to get the attention of shoppers – the loss leader. That is, selling a very small number of desirable items below cost to get buyers through the door.

Online marketing expert Michael Callaghan says landing a $25 TV or a $4 Playstation will be almost impossible for the average consumer. There will be very limited stock available and professional buyers will be at the head of the queue.

“The average Joe consumer has got a lot against them if they think they are going to get one of these bargains … it’s a promotional scam,” Mr Callaghan, a fellow at the Australian Marketing Institute and Deakin University academic, told The New Daily.

“The reality is this is a very old, recycled trick from all the way back to the first direct-marketing letterbox experience. It’s classic bait and switch – they are sucking you in with a very great deal on one particular item and your chances of getting that item are actually very low.”

In 2012, the promise of bargains went unfulfilled when the Click Frenzy servers crashed, robbing consumers of the chance to shop and denying brands the chance to sell.

Still, organisers say there’s something in it for both shoppers and retailers.

“We get retailers that normally don’t discount doing exceptional deals just because it is that single 24-hour event just a few times a year. It is a rare opportunity for them to give consumers something special,” Click Frenzy co-founder Grant Arnott told The New Daily.

“What we try and do is find quiet times for retail when consumers are looking for a way to get fantastic deals and retailers are looking for a boost to their sales. It’s a win-win and we’ve managed to create several really strong peaks of activity during November [its flagship Click Frenzy event] and in May [Click Frenzy Mayhem].”

However, average Australians face a severe disadvantage against what Mr Callaghan calls “professional online purchasers”, who make sure they get the high-value sale items before everybody else.

“There are winners and losers and the people that win in these sorts of sales events are the ones who approach it seriously, and can dedicate the time to sit online to be there at the optimal point and take advantage of it,” he said.

“If you’re an average consumer just logging on around about the sale time, I can guarantee that you’re not going to be able to get a slice.”

Australians have such a love for a bargain it spawned the forum website Ozbargain, in which users share when and where they can find the best discount.

“These people will have multiple computers, multiple browsers, multiple tabs open and they’ll be the ones who have the page open right at the exact spot so that they can click at the right time and make sure they have an overwhelming advantage,” Mr Callaghan said.

Click Frenzy’s Mr Arnott expects up to 1.5 million Australians to flood the online shopping platform, but could host 3-4 million consumers in the 24-hour period – the most in its three-year history.