The shop of every trucking company I have driven for has had such stock on hand for repairs. The crews of most of those shops would likely help you out.
When I was hauling steel on flat bed trucks, every fabricator I delivered to had a scrap pile. I have bought some steel from one, been given some by another.
Run a search on "industrial metal supply" plus your location. My local outfit, one I have hauled steel to, has a cutoff bin with bits and pieces left from other customers' projects, sells them by weight.