Here is a list of Resources that are not available on planets in game but are listed on Galaxy Harvester.
Dantooine, Endor, Mustafar
Dantooine, Dathomir, Endor, Kashyyyk, Lok
Corellia, Dantooine, Dathomir, Endor, Rori, Yavin 4
Corellia, Dathomir, Kashyyyk, Lok, Mustafar, Yavin 4
Mustafar. (this one I am not sure of)