With the Diablo 3 markets slowing down and thousands of players leaving the game every day, it's been difficult to justify spending time in the game playing the auction house. I've been making a couple million gold a day consistently for the last few weeks and selling off a bit, but I've even had gold that did not sell on the RMAH. What I'm telling myself now is that the hard work I'm putting in to raise my gold balance and keep in touch with the market will help make me a pile of money when they finally release the PVP patch...which apparently isn't going to be for a while.
Patch 1.0.4 will not have PVP as far as we know. They just released that they will be addressing legendary items, class mechanics, magic find, and a few other things. I don't think that this patch will fix the game, but it will bring a few players back to try out the new mechanics. I'm going to keep a close eye on how Magic Find changes. That might be a solid market to invest in as more players will want to try out Magic Find after the patch.
For right now, I'm doing my best to always keep 10 auctions up and have as many bids in to keep my inventory of items up there. Looking for items to buy out and flip is simply not viable for my play style as when I'm playing the game, most other players are sleeping and not farming. However, I've got a routine down of checking 7-10 different markets for cheap items to bid on every day. I'm keeping an inventory of 30-50 items to resell at any time and logging in every morning and every evening to put items up. Right now I'm spending around an hour a day placing bids and auctions (I haven't killed a demon in weeks).