If it's a seasonal exotic vanity item(not sure about ornaments(excluding live event ornaments)), you can't get those anymore. Season 2 probably had the most Eververse Exotic vanity items, and they are unobtainable now. Unless Eververse gets some kind of error where she might accidentally sell a previous season's exotic vanity item, they won't ever be available, but Legendary shells, ghosts, and emotes can still be sold.