The Amazon UK website was temporarily closed after a pricing error on its website saw pocket personal computers being sold for just £7.
The Hewlett Packard pocket computers were simultaneously retailing for $299 (£192) on the US site.
E-mails alerting shoppers to Amazon UK's mistake were circulating on Wednesday morning, prompting a rush of buying.
In the City, some workers were rumoured to be placing orders for 50 or 60 of the computers at a time.
The Amazon UK site temporarily closed at about 1240 GMT for 50 minutes and shoppers were redirected to the international site.
Amazon issued a statement admitting the error and cancelling the orders which had been placed at the incorrect price.
The firm said that its pricing policy allowed it to contact customers and offer them the product at the true price should an error occur.
"Despite our best efforts, with the millions of items available on our website, unfortunately pricing errors can occur," a spokesman said.
A higher quality pocket computer had also been on offer for £23 rather than its true retail price of more than £500.
Stuart Clary, a 26 year-old media worker placed an order for 12 of the more expensive computers, one for each of his colleagues.
"I wish I'd done more," he said, after saying he'd bought products worth more than £6,000 for less than £300.
Chris Partridge, a 27-year old network analyst, managed to snap up two of the cheaper variety but was not confident that Amazon would honour the commitment.
"I was looking for a pocket computer anyway," he said, "so will be very happy if it comes to fruition."
Customer services had previously told at least one customer that the price would be honoured.
But a spokeswoman for the Consumer's Association said the company was under no obligation to honour the price, if a genuine mistake had been made.
"Until there is a binding contract, either party can pull out of the agreement," she said.
Amazon's conditions of use state there is no contract between the company and a customer until Amazon sends an e-mail confirming it has dispatched an order.
A case last year involving Kodak seems to back Amazon's stance.
By mistake Kodak was selling the EasyShare DX3700 digital camera on its website for £100 instead of its normal price of £329.
Customers flocked to buy the camera. Initially Kodak said it would not honour the purchases, but eventually backed down.
This was because Kodak had sent an automated response to its customers, and that action effectively constituted an acceptance of the £100 offer.
Lawyers at the time warned companies to tighten up on their terms and conditions and to avoid sending automated responses to purchases.
This is a point which Amazon appears to have heeded.