Can't you just trade with him to get the necklace, too? I believe it's in his inventory.
Also, you can get two sets of Dragonplate this way, by buying it from the Dwarven Smith after he makes it for you. <img src="/ubbthreads/images/graemlins/winkwink.gif" alt="" /> <img src="/ubbthreads/images/graemlins/delight.gif" alt="" />