Reach Amazon & Ebay Seller

We have a tool that is useful for auto parts amazon and eBay sellers. We want to show our advertisement only for those people. Please give me the way of the paid marketing which we can follow. Also, what are your fees and how much budget do I need to spend if you can give me a rough idea that will be great too. Also if you have any plan for marketing in china I am open to doing that too.