I have a small stainless cup with handle, about 10cm I got from a fleamarket. It was $1 and weighs 2.04 oz. Very thin metal. Whole box of them from china.
I think some others have said they have seen them around too.
The flea market near me is the only place I have ever seen it. Ironic isnt it $30 for Ti cup that weighs 2.8 oz, or $1 for ss cup that weighs 2.04 oz.