Black Friday comes but once a year - while shoppers like bargains all year round. However, super-cheap purchases may not always be quite what they seem.
The problem's often most noticeable with clothes: this summer, for example, we reported on a woman who bought a $300 replica of a £4,000 wedding dress, only to discover that what should have been high quality beading turned out to be randomly-positioned cheap plastic sequins.
Other purchases listed on the Knock Off Nightmares Facebook page include shapeless sacks instead of tailored dresses, skirts that barely reach down to the hips and mis-spelled slogan sweatshirts.
However, it's not only clothes that can fall wide of the mark when purchased online: we look at some of the most widely-counterfeited products, and how you can steer clear of the fakes.
While there's always a certain amount of price variation between retailers, if you see something at half the usual price or less, there's probably something wrong. It may be stolen, a grey-market import on which tax hasn't been paid or simply a fake - even if you're buying from a reputable reseller.
It's not easy to tell in advance, as scammers will generally use photos of the genuine products, along with the real technical specs. However, it's worth checking for anomalies - a product being listed in a non-standard colour, for example.
If you're really determined to buy, use a credit card when spending more than £100, as this should give you protection.
Parents will often move heaven and earth to get the latest must-have toy for their little darlings - which is why so many fakes abound.
Disney toys are often the most counterfeited: last December, for example, knock-off toys from the Maleficent film were seized in Warwickshire and found to contain 18 times the the legal limit of phthalates - linked with cancer, asthma and decreased fertility.
This Christmas, no doubt, the fakes will reappear. Tradings Standards advises parents to buy only from reputable shops and beware of products that are drastically cheaper than they should be. And remember that however desperate your kids may be, it's never worth risking their health.
Last year, the UK's Medicines and Healthcare products Regulatory Agency (MHRA) seized dangerous counterfeit and unlicensed medicines worth nearly £16 million and closed down nearly 1,400 dodgy websites.
Despite this, the trade in fake drugs - and particularly Viagra - continues to boom. But much of what's sold online is either useless or highly dangerous, with fake medicines having been found to contain everything from printer ink to lead paint and even rat poison.
While it is legal for online pharmacies to sell to the public, it's important to check that they're the real thing. If they're legitimate, they should be registered with the General Pharmaceutical Council and display a logo that you can click on to see their listing.
However, erectile dysfunction pills such as Viagra can't legally be sold in the UK without a prescription - meaning that anything you buy online has a chance of being a fake.