For IU gear I buy from “Indiana University Surplus Store”. They have a Facebook page and post links to sales/auctions regularly. They sell literally anything of value from IU but in batches they have athletic gear. Helmets; Jerseys; Warm Ups. You name it. All authentic, most of it is game worn. I have two jerseys from them and one helmet. Hope that helps. Otherwise you gotta find one of those custom jersey makers in Asia and hope for the best