We can't buy wild gladiator's class sets, beacuse it's missing from the vendor.
checked, that alliance side is fine, only horde side miss this.
Checked again, and it's not just faction specific bug, it's also class specific, the classes listed below are miss their class sets:
Shaman ( http://www.wowhead.com/itemset=-1192/wild-gladiators-wartide )
Mage ( http://www.wowhead.com/itemset=-1187/wild-gladiators-regalia )
Warlock ( http://www.wowhead.com/itemset=-1193/wild-gladiators-felshroud )
Druid ( http://www.wowhead.com/itemset=-1185/wild-gladiators-sanctuary )
Paladin ( http://www.wowhead.com/itemset=-1189/wild-gladiators-vindication )
Priest ( http://www.wowhead.com/itemset=-1112/primal-gladiators-investiture )
Mage ( http://www.wowhead.com/itemset=-1187/wild-gladiators-regalia trousers are avaiable for the alliance, but other setparts are missing, horde missing all setpart)
Monk ( http://www.wowhead.com/itemset=-1177/wild-gladiators-ironskin )