A jewelcrafter, an alchemist and a scribe are my high level characters, so I can't make high end gear. But my pockets are overflowing from the profits I make selling green drops from questing. While I've been able to sell uncommon gear throughout leveling my pandaren monk, the armor that has dropped while in the 80s has been particularly lucrative. In general, the weapons aren't worth spending the inordinately expensive deposit to list, but most of my other green drops are selling after one or two listings. I can make some profits from my gems, potions and glyphs, but nothing compares to the uncommon gear market on my low pop server.
Now, I know people are reticent to give away their top money-making secrets. But there are enough servers with varying economies to make it relatively safe to reveal the items that make money for you. What works on your server may not work on another realm type or level of population. But I can still see where you may not want to risk it.
Yet I'm asking just the same. What is your big money maker on the Auction House? Does it vary according to what days of the week you list it? If you don't want to reveal your secret, at least tell us if you have a big money maker or if you're finding it hard to sell things you used to be able to sell.