I was recently talking to a guild mate who is rich from selling about 80k worth of titanium when that new patch came out
on my server (barthilas) there is about 3-4 people who sell 80-100k of stuff on the ah daily. They pretty much control what anything is sold for. Mostly boe patterns and gear are the biggest movers these days. But he says they also sell bulk stock but on multiple toons so as not to cause undercutting by others after seeing 1toon selling 200 stacks of titanium ore.
What I got from his wisdom is you need to be watching the AH all the time to pick up the bargains as there is always people trying to find the same bargains as you. Scanning twice a day is nowhere near enough. I farm heroics on my tank like a trojan when I can ( video card died 2 days ago so I'm reduced to browsing forums on my iPhone) after the gold reward and selling enchanting mats I don't bother playing the ah.