Complex PHP Search Function

Hi, I run a price comparison website. All the products are contained in a database and each row also contains the name of the retailer it comes from. I need the search to run like this: User enters a product name -> If a very close match is found take user to the page of the closest match else show user results to choose from. When a user goes onto the page of the closest match, it will show the closest match at the top with the retailers name. Now, we will use the closest matches product name as the new keyword search term, then underneath it will search through all the other retailers to attempt to find the same product from their store. If the result isn't the same it should show "N/A", but if it is the same it should display the product name. It is very important that when it tries to match the product from the other retailers that it is very accurate, and doesn't give "similar" products.