The thing is you’re going to be able to run this commission free exchange, cause it wouldn’t be easy for you doing this for free. There will be lots of things you will have to do and without money you wouldn’t be able to do it, unless you’re very rich and you want to be doing this for free and be spending the money from your pocket and using another source of income to make up for it, that will be up to you. I have seen one exchange that is similar to what you want to do, and that’s Cobinhood, but I think there is a particular they charge, can’t remember what it is though, maybe you check it out.