Jesyvut The regional vendor in the nation that holds Zulkheim will always sell semolina irrespective of that nations place.
Benaige's stock is dependent on both San D'Oria's position in conquest and whether you are San D'Orian Semolina only sold when San D'Oria in 1st or 2nd see link http://wiki.ffxiclopedia.org/wiki/Benaige