Looking for an custom eBay file exchange UI api to list products to ebay via upload.

We are looking for someone to make a UI that can interact with File Exchange or eBays API to list products onto eBay. We would provide all the categories we need and different attributes we will need to list these items onto eBay. Example: We want to list a pair of shoes on eBay. Shoes would then be one of our brands and each time we want to list a pair of shoes on eBay the api would ask us anything that might be related to the brand shoes. What size are they, what brand, what color, do they have cleats, etc. We provide all the Brands to you and the attributes of each brand. You make the UI that will write to a file ebay can import via File exchange. Ideally we will be able to support many users listing using the same UI and then at the end of the day it would write all things to the ebay file and we could upload this to ebay. Also, this would need to track items that already exists and simply allow the ability to add plus one to inventory. We will accomplish this by using custom sku numbers for each item that is listed and a database. Please ask questions..