Sorry to piss on everyones cornflakes but:
http://www.tradingstandards.gov.uk/cgi-bin/calitem.cgi?file=ADV1011-1111.txt
"The price on display, such as the price on the actual goods, the shelf edge price, the price given in an advertisement or on a website in most cases forms part of what the law terms 'an invitation to treat'. In these circumstances, this means that the price given by the trader forms part of an invitation for the prospective buyer to make an offer to buy, which the trader is entitled to either accept or reject. The buyer cannot insist that a trader sells anything at the marked price, whether or not the trader has made a mistake."
For those people that are hoping the orders are automated and sent to dispatch and they won't check, good luck.
Where I work, we do security checks before processing any order to check for fraud so a mistake like this would be noticed.
If you do receive the product at that price then well done but I can't be bothered to order!