Do you have old architectural detailing in your apartment that needs repair? Or do you just want to add some? Then try Dyke's Lumber. They're a fantastic local supplier of wood mouldings, among many other building materials like doors, windows, and custom millwork.
They have tons of crown mouldings, bases, and paneling in many, many different profiles. If you're trying to match something and can't find it here, they can do custom mouldings, too.