Here are the new values returned by the usEN as of 4.0.6:
GetAuctionItemSubClasses(1) => "One-Handed Axes", "Two-Handed Axes", "Bows", "Guns", "One-Handed Maces",
"Two-Handed Maces", "Polearms", "One-Handed Swords", "Two-Handed Swords",
"Staves", "Fist Weapons", "Miscellaneous", "Daggers", "Thrown", "Crossbows",
"Wands", "Fishing Poles"
GetAuctionItemSubClasses(2) => "Miscellaneous", "Cloth", "Leather", "Mail", "Plate", "Shields", "Relic"
GetAuctionItemSubClasses(3) => "Bag", "Herb Bag", "Enchanting Bag", "Engineering Bag", "Gem Bag", "Mining Bag",
"Leatherworking Bag", "Inscription Bag", "Tackle Box"
GetAuctionItemSubClasses(4) => "Food & Drink", "Potion", "Elixir", "Flask", "Bandage", "Item Enhancement", "Scroll", "Other"
GetAuctionItemSubClasses(5) => "Warrior", "Paladin", "Hunter", "Rogue", "Priest", "Death Knight", "Shaman", "Mage", "Warlock", "Druid"
GetAuctionItemSubClasses(6) => "Elemental", "Cloth", "Leather", "Metal & Stone", "Meat", "Herb", "Enchanting",
"Jewelcrafting", "Parts", "Devices", "Explosives", "Materials", "Other", "Item Enchantment"
GetAuctionItemSubClasses(7) => "Book", "Leatherworking", "Tailoring", "Engineering", "Blacksmithing", "Cooking",
"Alchemy", "First Aid", "Enchanting", "Fishing", "Jewelcrafting", "Inscription"
GetAuctionItemSubClasses(8) => "Red", "Blue", "Yellow", "Purple", "Green", "Orange", "Meta", "Simple", "Prismatic", "Cogwheel"
GetAuctionItemSubClasses(9) => "Junk", "Reagent", "Pet", "Holiday", "Other", "Mount"