The blunder was live for several hours although it has now been removed from the site.
It is the second error in a week. Earlier a Sony handheld computer worth £319 was advertised on the website for £139.
E-Comet's Vice President Simon Rigby said that the company is investigating the matter and apologised to customers affected.
Customer rights
Those who had only received a first e-mail confirmation of their order will not have their contracts honoured said the company.
"The first e-mail is just an acknowledgement and doesn't constitute a contract of sale," said a spokeswoman.
Mr Rigby added that customers who have received a second e-mail will get the goods they ordered.
Robin Bynoe, partner with law firm Charles Russell, argued that customers who have placed an order are legally entitled to the goods they ordered.
"An e-mail confirmation is a binding contract. I can't think of any way that Comet can't honour it," he said.
It is the latest in a line of embarrassing blunders for online retailers.
Back in 1999 Argos offered customers a £300 TV for just £3. Hundreds of orders were placed before the error was removed.
After consulting its lawyers, Argos decided not to honour the contracts.
Kodak did pay out for its web error, when a digital camera worth £329 went on sale for £100 earlier this year.