The plans for the shield spikes, iron counterweights and steel weapon chains are all dropped and thus cannot be purchased at any of the trainers. Iron shield spike and iron counterweight plans are the most commonly up for sale in the auction house, of the plans you want. The higher shield spikes as well as the steel weapon chains are rarely up. They probably get bought out very fast.
60 Warlock ~ Illidan ~ Marvel ~ WOW
60 Warrior ~ Illidan ~ Marvel ~ WOW
70 Enchanter ~ Fennin Ro ~ T`Kagi Ro ~ EQ