The online equivalent of Black Friday takes place today.
One in three brands will be offering discounts for Cyber Monday, with bargain hunters expected to spend an extra €53m online.
People are being reminded to know their consumer rights and to buy from reputable websites.
Many retailers have promised a host of new deals for the culmination of the four-day pre-Christmas shopping event, which kicked off with Black Friday.
Retailers have been attempting to lure shoppers in with deals for more than two weeks now in an extension of the traditional one-day Black Friday event.
Cyber Monday has also always been a strictly 24-hour event, and online only - rather than in stores and online on Black Friday.
But analysts say the short-lived spree has evolved into a more extended period as consumers learn to track prices and compare deals between retailers in the weeks leading up to Christmas.