A couple of days ago I posted a link to Blackstar to get Lord of the Rings, The Fellowship of the Ring for 99p - £3.99 for the DVD and a £3 voucher. The day after, the price of the DVD suddenly increased to £17.99. Well, I received an email from them today saying

You have placed an order for The Lord Of The Rings: The Fellowship Of The Ring which was priced at 3.99 GBP. However, this item was only available
at this price if purchased in conjunction with The Lord Of The Rings: The
Two Towers at a combined price of 19.99 GBP. Unfortunately our suppliers
will only release supplies of this item at 3.99 GBP if we sell both of
these DVDs together for 19.99 GBP.

We will therefore cancel your order for The Fellowship of The Ring as a single item and your credit card will not be charged.

There have been cases in the past where products have been advertised at the wrong price, and retailers have handled it differently. Last year Kodak mistakenly offered a digital camera for £100 instead of £300, and in March this year Amazon had an iPaq on sale for £7.32 instead of £300. Kodak eventually bowed to pressure and honoured the price on the cameras, whereas Amazon did not. The difference between the two is that it was obvious that the Amazon price was a genuine mistake, whereas Kodak's could have been interpreted as a genuine offer.

Blackstar's Terms and Conditions give them a getout clause though, as they say there is no contract for the sale of the goods until they are shipped (altough whether that has been changed since is impossible to say).

Were they right to cancel the orders? Yes, probably, they seem to have the law on their side. Was it good business to cancel them? No, not really. If it had been an obvious mistake, say 50p, then I would understand it, but there was no mention on the page that it was only available at £3.99 if both films were bought at the same time, and £3.99 for a DVD isn't an obvious mistake.