I found a new place for gold farming, Shadowmoon Valley, specifically the Ruins of Karabor. You can see the exact location on this map:

There are plenty of targets, as you can see:

The trick is to let them beat on each other a bit:

And they have pretty consistent drops like this:

The Sunfury Signets go for about 1g on my server, and they drop about 20% of the time according to thott

I usually try and sell them in the zone over the general channel. I can sell them for more because people are grinding and want to get done. Like everything, they go for more on the weekends.