Make friends with chinese farmers, they live in Azshara and Tyr's hand mostly... I have three different farmers that I buy felcloth from, 20felcloth/2g, I just throw some 'complex' (basic/gibberish) math at them, and they take the bate.
Me: do you have any [Felcloth]?
them: want [Felcloth]? 2/1g 5/2g yes?
Me: how about this: 2=1, 5=2 5*4=20 20/2^2=5 5/2.5=2 . You understand, right?
them:...yes....
Me: good, 20 [Felcloth], 2g is fair, yes?
them: open trade
BAM! 60+felcloth a day, and now I supply other guildies with it for 2/1g and make massive profits (they don't attempt to buy it from others, because I give the best deals).
Note: make sure you talk to the farmer who understands your haphazard logic at THE SAME TIME EACH DAY, because farmers do share accounts. If you go on too much later, they may have already changed shifts.
The method which works best for equipment is this:
when a farmer (someone who spams massive amounts of cloth/items) starts advertising a nice piece of quipment, first make contact with them, so they stop.
This whole conversation must take place in tells, otherwise someone else might see the equipment and accept the initial price.
Me: How much for [Rare equipment]
them: 50g
Me: ( to friend) broadcast [Rare equipment] in IF channel for 5g
My friend: Ok, gimme a sec
Me: 50g sounds awfully high, 10 sounds more fair...
Them: 40g yes? no lower.
My friend (IF Trade): WTS [Rare Equipment], 5g
Me: NM, someones selling it for 5g in IF trade
them: wait! 8g yes?
Me: fine, I guess I sort of owe it to you.
them: open trade
Since Farmers already often times sell things very cheap, you can make quite a bit of money off of them, or get nice items for yourself.
Although I do occasionally feel bad about this, while trying to make some money in Azshara, certain farmers screwed me over pretty badly, so I consider it to be retribution.
I'm sure this is post #600000 about farmer manipulation, but details have to count for something ^^