One of the ways that allows me to continue to make a good profit, is be befriending farmers. Farmer used to be a nasty word, but learn to take advantage of random farmers. This is a lot easier since the addition of Note tags for your friends list.
Next time you are at the auction house and notice the same person selling a lot of stacks of the items you are buying, try to contact them to set up a steady flow of incoming materials. After you buy them all out off the AH, send then a quick email in game, asking to skip the AH and COD the items directly to you for a price clsoe to their buyout price. You can create a win-win situation here. Not only do you save the farmer time and money, you also can get a lower price, thanks to the removal of AH fees. I usually send a quick email that says, "I will buy X item for X gold per stack. COD them to me any amount anytime." Some farmers supplying me daily. Others supply me sporadically. Either way it a big bonus for any crafter / shuffler.
This allows a smart farmer to maximize time and profits. Avoiding the AH fee, avoiding the time it takes to post on the AH, and allowing the ability to MAIL COD to remove items from bag slots. So when the farmer fills his bags he can just visit the closest mailbox, instead of a major city with an AH. Depending on the farming location, this can be a HUGE advantage.
As a bonus, sometimes you will continue to get items COD to you at pre-patch prices after the value has gone up. :)
This process is most easily done with the farmers of raw materials, such as: Ore, Bars, Cloth, Food, etc.