Price Comparison Script (oscommerce,magento,zencart)

Hi Looking to start a price comparison Website for a certain Market audience We have a list of several Merchants that each uses differnet software systems for their online store i.e Zencart, OScommerce, Magento What we want developed is some sort of connector that looks at Live prices on the Merchants website and return the results to our website So for example - User logs in to our Website - User searches for example "Guide to River Fishing" - Site then Searches Merchant Site for Live Prices - Site then returns prices from all merchant sites and displays them alphabetically - User can then Sort results from high to low and vice versa and is able to complete the purchase by clicking buy now and it redirects them to merchant site Thats how it will work,it needs to be based on LIVE prices direct from the merchants website From the admin end - i need the option of Adding Merchants (Along with contact details and list of merchants etc) - Track Searches made by users - Track Clicks made by users I dont need design or anything just the script and connector Please post price, and how long it will take