IWM miniatures basically don't go out of production. At least one, the Bombardier, was being continually produced since the Battledroids days right up until it was resculpted in 2010 or so. I think the only miniatures that were straight-up removed from production were the Battledroids pieces, the Unseen (obviously), and the limited-edition Leviathan from a tournament, but still different versions of all those pieces can be ordered.