Psst! Want a cheap PC?

It was a grey Saturday morning as I headed for London Computer Auctions in Edmonton, north London. I felt wary but optimistic. Whether you are bidding pounds 5m for an Impressionist painting or pounds 1 for a modem, there is a feeling of excitement in an auction room. In both cases, the experts glory in the traps that await the unwary.

10am: Arrive at the venue, a warehouse between a concrete plant and a cemetery. Racks hold rows of computer systems and printers. On the floor are cardboard boxes holding handy lots such as five Swedish keyboards and 500 used floppy disks.

A dozen early birds are inspecting the goods. One gives me the 30-second guide: "If machines are in sealed boxes, they have checked them; if they are in the open, it's anybody's guess. New systems are sold with the manufacturer's warranty. For anything else, you get a 24-hour warranty if it costs over pounds 200." The message is to try before you buy. There is a test area, where you can even inspect the internals of PCs - under supervision, because a lot of coveted computer memory has been spirited away.

10.15: Tour the second-hand machines. Many bear labels from previous lives. One reads "DOT - Accounts". I wonder whether the poor woman has had to resort to an abacus, but DOT turns out to be Department of Transport. London Computer Auctions acts for government departments, selling thousands of machines on their behalf.

10.30: Four hyperactive teenagers arrive, determined to impress. They unload a new 486 from its packaging with a thud. The expert in the group says: "What's it like? Just show us the fascia - looks all right, dunnit?" An elderly gentleman is taking photographs of a large cardboard box.

10.45: Head for the test area, looking for tips. A family is inspecting a sleek 386 system box and has drawn a crowd. After linking the box to a screen that was lying around, they switch it on and an error message appears. I would have stopped here, but Dad has brought his own floppy discs to try to get the machine started. They do - and reveal that the computer doesn't have a hard disk. "You could add a standard hard disk for around pounds 120, so I would bid to pounds 40 for this," says Dad.

A couple are trying to piece together an Apricot system, but the keyboard doesn't fit. "Is there someone we can complain to?" she asks. "You don't complain," says her husband. "This is an auction. You go and look at something else."

10.55: With five minutes to go before Lot One comes under the hammer, there is frantic activity. "Oh no," says a man crouching on all fours in front of a screen. "This one needs a password." "That's OK," replies his colleague. "The user wrote it on this label." They negotiate a screenful of programming gobbledegook to find out what the PC holds: "Look - somebody's files. This isn't a government machine, or all the data would have been wiped off."

11.00: The auctioneer, John Russell, takes a deep breath and starts selling. Lot number one ("I believe it is a 386, but you should draw your own conclusions") goes for pounds 50. When you are planning your budget, you have to allow for VAT and a 5 per cent buyer's premium on top of the bid price. Action is fast, and punctuated by the banging of John's gavel very hard on his desk - so hard I wonder how the clerk's computer beside him survives the vibration.

New machines fetch a reasonable amount. A Pentium goes for pounds 820, and the 486-with-the-fascia is bid up to pounds 590, which stuns the hyperactive youths. Large consignments of identical items are offered separately, but the buyer of the first lot gets the option of taking the others at the same price.

12.15: Time for the software section: "An encyclopaedia on CD-Rom, pounds 12 to the man in the Burnley football shirt." "It's Arbroath, actually." There is a good selection of business software, new and boxed. Prices seem remarkably low, particularly if you don't need the latest version.

Amid all the activity, John Russell finds time to acknowledge some regular faces in the 80-strong audience. One is Father Brian Smith, vicar of St Peter's, Edmonton. He acquired his first computer at auction five years ago, and still buys. He uses a PC for everything from designing personalised orders of service to printing out music for the organist. Last year, LCA held an auction in aid of Bosnian children and the St Peter's technology fund. His advice for bidders: "Go along to watch and learn. Then set a spending limit, and keep to it."

2.15: Prices are falling as less fashionable items come up: an old office laser printer (pounds 10), a new infra-red printer (pounds 10), a photocopier (pounds 22) and the Times and Sunday Times on CD (pounds 5). The catalogue is peppered with acronyms, but John Russell is happy to fill in the detail: "A 286 model 38. The documentation is incomplete, but that shouldn't be a problem: people are always willing to do you favours. A CM-205 CD-Rom. The installation manual is wrong. We can advise you, but it's not straightforward."

3.00: Next lot is an arcade games console, complete with joysticks and steering wheel, and finished in classic purple and yellow swirls. I've had my eye on this one, but I think of the transport costs and keep my hand down. The machine goes for pounds 24.

4.15: Only 10 people remain, and prices have plummeted. Mike Bayliss, a dealer, sums up: "Today a good 386 was making around pounds 150, but prices tend to be lower when there are more machines - sometimes there are hundreds - or when it's Cup Final day. Old computers aren't fashionable, but they are perfectly good for word processing. You might get a batch of second- hand PCs where 95 per cent work, the rest maybe not. When you are testing one, at least confirm that it boots up to the DOS 'C' prompt without error messages, all the keys work, the monitor looks fine and you can read and write to a floppy disk. Like a car, a PC with a service record is a good sign. If you take a gamble, it's like a flutter on the horses. I'd put a fiver on that, but not pounds 20. Good fun, though."

London Computer Auctions: The Auction House, Pegamoid Road, Edmonton, London N18. Tel: 0181 345 6535.