Another tip pointed out by MoneySavingExpert.com

Amazon operate a rather strange refund policy - if you buy something and then find that they have reduced the price within 30 days then you are entitled to contact them and ask for a refund of the difference so you basically pay the new lower price.

This is obviously a good time of year to be finding this out as a lot of people would make purchases in December prior to Christmas only to now see the goods in the inevitable January Sale.