Salam alikoum my friends, I would like to express my personal opinion on this matter first, the fact that the tendency of doing business nowadays is changing requires from us and more specifically from our scholars the people who know business, economy, laws, the islamic religion and history well to make Ijtihad and give us relevant answers to our daily needs. To answer your question, I have myself looked for a true, honest answer to selling reproductions, factory variants you could call them or fake shoes and what I came to is as long as you are not lying to your customers, insh'allah it will be fine, the thing is you have to be honest with your customers, state clearly that you are selling shoes that are made in china, variants, shoes in colours that have not been released etc if you look at the international seen now, millions of people are making a living out of selling these fake shoes, and on the other hand millions of customers are buying them simply cause they can afford them, cause there is more choice in sizes, colours etc
I myself after a long period of asking scholars etc came to the conclusion that as long as you don't lie to your customers you should be fine insh'allah.
I am in the online business selling these shoes, elhamduleh I sleep well at night simply cause i'm not lying to anybody and obviously making my best to offer the best service possible.