I don't know if these folks do bras small enough, but this is the one that I immediately thought of when you posted:
http://www.ntac.org/news/01/01/06max.html

I know there was a place in England that is the perfect place for you (caters to women with large breasts, but who are not otherwise "plus size," but I can't think of the name. I think I gave the catalog to grynz, so maybe she'll know.