WHITE SEDUCTRESS: This outfit was released in trove a year or so ago
DARK PHOENIX: Was released either during an event, HM Store, or another Trove
PHOENIX OUTFIT: Was released in HM Store for almost $50 - $55 in NCoins.
When you look at the outfits in the Storeroom, look at the category it is under, it will tell you which zone/place the outfit could be or where it was sold. The outfits you have been looking for were in HM Store/Event.
NCSoft has put some outfits for sale if you go to the vendor that is in Zaiwei, you can buy some for Fabrics/High Fabrics. The Cosmetic Vendor sells old event outfits for Yarn and whatever that other thing was.