Hey, I know this isn't a tactic much used before, but I think I just invented a great way to get some nice money.
The trick is to go to Steam Vaults (on normal difficulty), which is located in Zangarmarsh. A little decent gear is required, to be honest. So, don't be all green/blue. :yuck: I'm not saying it won't work with just blue/green gear, I'm saying things will get sooo much easier when you're better geared, it's a level 70 instance anyway.
So, the meaning of this run is to kill everything in your path (for Ret pallys, even the critters, to get your mana back). The mobs averagely drop around 50 silver, but unlike many other instances, they really do drop a lot of other stuff as well, including gray items, greenies you should vendor, and ofc, the bop rare drops. One run averagely gives me like... 50g, which is only the cash they give. After selling the grays/greenies/bop rares, it's getting close to 100g.
But THE thing you'll need to gather as much as possible of, is Coilfang Armaments. I had no idea before, but on my server, these things sell really quickly on AH, and for a lot of gold. Probably for those people who try to get rep with Cenarion, most likely to get the Guardian of Cenarion title. So, my aim has always been not to leave Steam Vaults (ofc, I do run out sometimes and reset it to redo it all several times) area until I have 50+ Coilfang Armaments. On my server, 50-60 of these sell for 300g or more. I don't know about other servers, but this has proven to be very useful for me.And of course, if you're at least a little decently geared, like Naxx10+, in two hours, you could do like 3-4 Steam Vault-runs, which would bring you very close to 200-300g in cash/trash/greenies/bop rares, and another 300g from the Coilfang Armaments.
There you go, I hope this experience of mine helps you too now.