Hi, I think this is a great idea, and it is a way that allows a seller to increase the amount they sell, and allows ebid to make more money, so a win-win.
Basically when a buyer buys an item they have the option to include maybe accessories or different things with the order that i set up to appear with a specific product.
Here is an example: I am selling an Android Tablet. And right after they clicks buy or before there would be a list of add-on products like a micro SD card, stylus, case etc. And the products could be discounted so the buyer thinks they are saving money and more likely to add it onto their purchase.