If you buy your stock from wholeseller / dropshipper or any other source that can deliver API or any type of files that will help you automate product updates, this service is dedicated to you. Depending on the available materials you can automate import and updates of products and their images, categories and manufacturers assignment and of course stock and price controll. Giving your own margin based on various factors will improve your earnings , while reducing work load. In many cases its also possible to automate or at least speedup of orders processing. Not sure if your meet requirements... just ask.