To answer briefly: - No, there are no other vendors than the ones you have seen. - Yes, you can obtain Mods and Enhancements from doing the dailies. The Heroic on Illum gives you an Enhancement, and the Heroic on Belsavis gives you a Mod. - So you can obtain all of your Armoring/Mod/Enhancement/Hilt/Barrels/Ear/Implants from doing the Illum and Belsavis dailies.