Greetings!
This is my first guide here!
As all we know the Engineering crafted trinket, the Ghost Iron Dragonling useable to everyone, not just Engineers! Its clearly... But maybe you dont know, the Cogwheels are very profitable nowdays! Cost of mats are max 4g (4 Ghost iron Ore or 2 Ghost Iron Bars). But you could sell Cogwheels 130-180g at AH!
The new cogwheels, which are now called Tinker's Gear Gems, are also useable by all characters instead of just Engineers like the previous versions. A Tinker's Gear Gem exists for all of the secondary statistics, but they are unique-equipped, so you can only socket one of each type.
Tinker's Gear Gems in MoP:
-Flashing Tinker's Gear - 600 Parry
-Fractured Tinker's Gear - 600 Mastery
-Precise Tinker's Gear - 600 Expertise
-Quick Tinker's Gear - 600 Haste
-Rigid Tinker's Gear - 600 Hit
-Smooth Tinker's Gear - 600 Critical Strike
-Sparkling Tinker's Gear - 600 Spirit
-Subtle Tinker's Gear - 600 Dodge
On my server the 3 of them are worth to sell :
-Fractured Tinker's Gear - 600 Mastery
-Quick Tinker's Gear - 600 Haste
-Rigid Tinker's Gear - 600 Hit
I sell them by 1-3 pcs 4-5 times/day. I use the web based AH for this. I make solid 2-3k gold/day with this and its max 20 mins/day
I hope you could make some easy money with this method!