One of my favorite ways to make gold, even though it's not the most lucrative business is selling items you can get straight out from the vendors. And what i mean by this is that you can rack up some fast and easy gold by just walking up next to the random vendor that's sitting usually next to the auction house or very close by.
You would think that i'm full of crap and that everything i'm saying possibly can't be true because lets face it why would you pay ten or even fifty times the worth of something that you can get from the vendor, well the answer is simple, people are either too lazy to walk to the vendor don't care or they are not informed but either way that's gold in your pocket.
I'll put down some items i've had insane margins selling like 500-1000% even though they are not expensive profit is profit.
Blacksmith Hammer 13c 10-20g
Mining Pick 57c 10-20g
Walnut Stock 3g 50s 10g
Hair Trigger 63s 10g
Enchanting Vellum 7s 1g per item, usually sell them in 3-5 stack size or 20
Coal 3s 50c 20-35g stack
Dust Of Disappearance 8g 75s 15-25g depending on competition
Those are some of the basic no brainer items you can post up on the AH and get some nice profits but i have to admit my favorite vendor items would be the items you buy off the Inscription Vendor in the Twilight Highlands, but for a better preview check it down below
(FOR THIS YOU NEED TO HAVE OPENED TWILIGHT HIGHLANDS PORTAL)
Una Kobuna sells
Deathwing Scale Fragment 4g 50s 125-175g
Bleached Jawbone 29g 60s 125-175g
Preserved Ogre Eye 24g 67s 125-175g
Scavenged Dragon Horn 12g 78s 125-175g
Silver Charm Bracelet 33g 41s 125-175g
One thing you need to remember about these items is that you need to leave an impression that they are rare and something worth buying and not something that's easy to obtain or give notice to the potential buyer then he can get it from a vendor by doing the silly thing and flooding the AH with them, so think smart and only post 1 of each at any given time and watch the gold come pouring down in due time.
The reason why these items sell at such a price is that all the scribes get access to the PvP items that they can craft but need these items but for some reason, be it that they dont know that it's sold by a vendor or haven't unlocked the vendor by doing the quests they decide to turn to the AH and in turn to fill up your pockets with gold.