I revisited an old farming spot of mine to see what kind of gold per hour it still generates. It's that cave in storm peaks I mentioned a long time ago to farm eternal fire. Here are my results after a 20 min farming session.
35x Crystallized Fire (20G an eternal)
30.5G worth of vendor greys
3 Greens that DE into 2xGreater cosmic Essence and a Dream Shard
So that was 150G in 20 min. If we expand that out to an hour, that's over 400G an hour. If you take your time and sell those as crystallized you can get 3g each instead of 2g (as an eternal). Doing that would bump it up to 500g an hour of farming time.
I farm these in a cave in storm peaks. It is in the upper left corner of the map. You see 2 caves. One is full of mobs that drop fire and the other they drop air.