Buying goods from the high street costs shoppers hundreds of pounds more than buying from online retailers.
The largest high street mark-ups are on toys, cookers and washing machines, according to research from TalkTalk.
For example, consumers could save £136 when buying a Hotpoint Double Electric cooker, priced at £364 at appliancesonline.co.uk, compared with £500 at Argos.
"The price gap between shopping online and on the high street has actually widened significantly in the past 12 months, reflected in the huge price differences we are seeing," says Trisita Clarke, commercial director at TalkTalk.
When comparing internet and high street prices of a random selection of 50 goods, the study found that online prices fell by 0.7% over the past 12 months, while in-store prices rose by 1.6%.
The study shows that over the past five years, high street prices have increased at double the rate of those of online retailers.
"Switching to internet retailers offers one way for households to get round the squeeze on their spending power," says Shehan Mohamed, economist at the Centre for Economics and Business Research.