Adding "co.uk" on to "estateagent", "homepages" "rightmove", "propertyproperty" "08004homes" gives access to large numbers of properties across the country.

For people who know exactly where they want to live the sites are of limited use. Even the most comprehensive will not be able to compete with a local newspaper.

But where they really come into their own is when someone wants to find out about house prices in a certain area whether with a view to choosing somewhere to live or buying a property to let. Those who are simply curious about property prices will also enjoy using these sites.

By far the best-designed site for researching prices is home.co.uk. It has nearly 200,000 property particulars, the majority being with estate agents, although private sellers can advertise their homes free.

While the information one can glean from this site will not be as accurate as the major house price indexes prepared by the Nationwide and Halifax, these only divide the country up into regions such as East Anglia and the south-west.

Prospective buyers can specify a type and size of property, an area of up to 80 miles across and a specific price range. Asking it to find a home for less than £50,000 within a 15-mile radius of London EC1 is an easy way to find out where the cheapest homes are in the capital. This somewhat scotches the popular wisdom that an income of £30,000 is necessary to get a foot on London's property ladder.

There are 21 homes avail able for under £46,000, which should be within the range of anyone earning £15,000 and having a small amount of savings. The cheapest are one-bedroom flats in Dagenham and Shooters Hill for £39,995.

At the other end of the scale one can find the most expensive properties by seeking those over £5m. Top is a 12-bedroom mansion with an acre of grounds near Holland Park at £15m. Prices fall to £21,400 in Basildon, followed by only slightly more expensive places in Maidstone, Sheerness and Rochester.

Birmingham is not always cheaper than the home counties, with prices starting at £22,500 for a one-bedroom flat in the Quinton area. The most expensive house within 20 miles of that city's centre is £900,000 for a six-bedroom house in Edgbaston.

Those desperate for a cheap property will find several in Sheffield, Newcastle and Liverpool for under £10,000.

Someone with a very specific area in mind can glean a good deal of information from the site that would have taken ages to obtain by identifying and ringing local agents. For instance, within ten miles of the Scottish border town of Newton St Boswells, there are 21 properties available from a £36,500 two-bedroom apartment to a detached country house for £285,000.

Some areas are not so well catered for though. Within the same distance of Haverfordwest in Pembrokeshire there were only four properties. That though is the exception and for the vast majority of the country home.co.uk has the potential to be used for relatively serious research.

• Richard Colbey is a barrister.