But the problem, for most individuals, is finding that information. One alternative to trawling through a vast number of websites is to turn to a specialist shopping service.
One of the highest-profile shopping sites is Valuemad, which is backed by Asda. You tell Valuemad what you want to buy, and it searches the internet - or more accurately, a selection of internet stores - for the products you want.
Valuemad concentrates on electrical hardware - including televisions, hi-fi equipment, video recorders and white goods - as well as books, music, computer software and travel.
The idea behind Valuemad is promising, and the site is easy to use. Unfortunately, although Valuemad is convenient, it does not save shoppers money.
A search for a Philips wide-screen digital television was frustrating. Dixons has a 28-inch model for sale at pounds 1,099.99, an attractive price, on its own website; Valuemad failed to find a match. A search for books produced a range of prices for JM Coetzee's Booker Prize winner Disgrace, but none bettered Amazon's own price of pounds 7.35 plus postage.
There is nothing wrong with Valuemad. But given the range of good deals on the net, it is something of a missed opportunity. If the service searched for prices from a wider range of suppliers, it would be a real draw for the internet's bargain hunters.
Cut your bills
Buy.co.uk steers clear of anything as glamorous as a television set. The website offers a similar service to Valuemad in seeking out the best deals, but it concentrates on day-to-day necessities like gas, electricity and water. It also covers the complicated area of mobile phone prices.
Buy provides some other interesting services. The e-lephant site reminds visitors about offers and promotions such as coupon deals in newspapers.
There is a section detailing the best online shopping services, ranging from cars to computers and electrical goods. Usefully, there is a facility to compare prices in the UK with the far more competitive US market.
You might not save thousands using Buy, but shaving pounds 30 off the gas and electricity bills will cover the cost of a good few hours on the net.
Stephen Pritchard can be contacted at Hifirstname.lastname@example.org