Make a raid and go in Zul'gurub, start farming all the trash there but i recommend that you skip the "Gurubashi Axe Thrower's" since they do some annoying and long stuns that may end up getting you killed. What you are farming is :
All the Bijou's, colour does not matter. For around 30 minutes i was able to get 20 Bijous, wich sell for 15g a piece in the ah, or if people on your realm dont actualy sell these make em 20g a piece but not more since nobody will buy them. People need these Bijous to raise their rep with the Zanadar Tribe so there will be alot of customers i guarantee it. I sell them sepherately since more people will buy them that way. So that's like 300g per 30 minutes or 600g a hour for me. If you dont get the idea for what bijous im speaking of
heres a picture Blue Hakkari Bijou - Item - World of Warcraft i randomly linked that picture , doesnt mean you gota farm the blue one speccificly.
Also if you are better geared and have a way to survive through some 95-111k HP mobs id advise you to go in to the Molten Core and start farming trash.
The trash drops Lava Core and Fiery Core - these moneymakers sell for 50g each ,but the drop rate is kinda low so you'll get like 1 lava or fiery core for every 10 monsters you've killed and if lucky you can also get some BoE epics wich i also sell around 30-40g each. These Core's are also used to gain reputation, with the Thorium Brotherhood or they can also be used to craft classic weapons, legendary materials etc so expect to have alot of costumers again. I grinded for an Hour There and i got 6 Lava Cores and 7 Fiery Cores + some BoE belt (worth 35gold in AH) so that makes is 685g in a hour.
But i also have to mention that its all a matter of luck - you might get a lot of drops or less drops