Automatic Pricing

We deal with Amazon, have thousands of listed products online. As we are a seller visually it is a huge list (250 items max on 1 page) with names of goods and other date including our current price for each product and the lowest price among our competitors in the next gap. We need a code which would sign in to our account automatically once in 5 min, check all prices and change ours in case if any of competitors' ones is more than we do. We must always be 1p less. We are interested in all Amazon platforms ([login to view URL], com, [login to view URL] etc) so your code must cover all of them (please note all Amazon sites are identical!).