E-commerce sites scrapper for optimum pricing

I need a software checking ebay prices for multiple items. I would like to upload product list (i.e 100 individual items or more) with UPC codes or item titles in an excel or similar format and get the results as a list containing each item, in excel or similar format. The main idea here is that I do not want to spend time for "pricing" task of my inventory and being able to find the "optimum" price automatically to gain competitive advantage. So, this software should also carry out some logical tasks (I do not know how??? average, median, etc.) in behind to provide me the optimum.... Please do not hesitate to ask for more details. Thanks.