Well, if you want orc armor you can find boots and a cuirass in Meldor's shop in Balmora (he is the armorer) or you can go to the place where the creeper is and if you go upstairs it`s some crates there and in one of them there lies a cuirass and some greaves and the only thing the orc who stands there say is "thief".

I would have thought orcish armour was common enough. There are several Daedric sites full of murderous orcs, Umbra has a full set, there are four round the shrine of Malacath near Dagon Fell and sometimes bits on the corpses discovered in caves and mines.

Most of the rampant orcs in the Dwemer ruin Mzuleft have a set. Valenvaryon also has a few angry Orcish-armour wearing Orcs.

Outside one of the daedric shrines under city of Vivec(i forgot which canton) there is an orc guarding the entrance who is easy to kill and has a full set or orcish armor.