A consumer investigation has revealed the huge variations in price of some of the most popular products for sale in the past year, with some items being almost twice the price at certain points.
During a year-long investigation, Which? tracked the prices of 32 of the most popular makes and models of home and technology appliances across five of the biggest retailers - Amazon, AO.com, Argos, Currys PC World and John Lewis.
The study found considerable variations in almost all products.
Which? also found several examples of products that had large price fluctuations in non-sales periods.
A vacuum cleaner (Vax Blade 32v) at AO.com that jumped by 54 per cent, costing £299 at its highest point but coming down to £139 at its cheapest.
There was also a fridge-freezer (Samsung RB29FWRNDBC) at John Lewis and a printer (Brother MFC-J5335DW) at Amazon that both varied in price by 43 per cent.
The random pricing policy from retailers makes it much harder for consumers to plan when to buy the products.
However, the investigation found there are some products that maintain a more steady price.
A notable example was the Apple AirPod headphones, with a consistent price of £159 at all the retailers looked at, except for a short period around Black Friday where they dropped in price before returning soon afterwards. Amazon offered the lowest prices more often than the other retailers, with the lowest price almost as often as all of the other four retailers put together.
Amazon had the absolute lowest price for 11 products – but in some instances not for long - and also had the lowest average price across the year for 15 products.
In contrast, Currys PC World had the highest number of most expensive prices although only just, and sometimes for a very short time. It was cheapest for two products in the investigation.
AO.com, Currys PC World and John Lewis all offer price-matching schemes, although these all have slightly different rules about what is included.
Alex Neill, Which? managing director of home products and services, advised consumers to research prices of items they wanted to buy.
“Whilst we expect price variation across the year, our research shows shoppers are often faced with wildly fluctuating prices and not necessarily during traditional sales periods.
Mr Neill added: “This can make it difficult for people to assess when a bargain is really a bargain, so we advise taking retailer hype with a pinch of salt, not feeling pressured by time-limited sales and doing your research before buying.”