The whole idea comes from PTR update on the item: Relic of Ulduar.
The specific item can be turned in stacks of 10 and increases the Sons of Hodir faction reputation by 250.
Due to the valuable rewards that you can acquire from “The Sons of Hodir faction” plus the difficulty it has currently to be raised, the value of these relics are going to hit the sky. According to my WoW economics experience they will be sold for 10g per piece after the patch comes live and at least for 1 week duration. After the first week it will start dropping its price to 5g per piece or even lower.
The ideal thing would be to farm them while farming Crystalized fire which sells for 5g / piece minimum.
The mobs that satisfy both of those criteria are the Seething Revenants which drop 40% relics and 30% 1.5 Crystalized fire. The specific mobs have very high respawn time which makes them ideal to farm even when there are other people farming them too.
Assuming that you can kill 3 mobs/minute (which is quite easy) its translated to 180 mobs / hour. With the specific drop rates its 1125 Gold / hour.
180 mobs * 0.4 = 72 relics, 72 relics * 10 gold = 720 gold
180 mobs * 0.3 * 1.5 = 81 Crystalized fire , 81 Crystalized fire * 5 gold = 405 gold
I hope I helped.