The best way I have found to make money in world of warcraft – is to branch out in many different markets, never staying with just one, and learning your server as patches and raids evolve and change. I happen to play on a lower population NA realm, and my sales differ compared to a high population. Things tend to move a bit slower, and potions are not a big seller on raid night compared to other servers.
That being said, there IS money to be made. It’s only by branching out that I get to discover this. Posted above is my most recent sales and flips. Items I purchased for one price and then sold for a higher price. When the market is flooded the price dives down, but on days where the items are used in a quest they tend to go way up. You can see my largest profit was from reselling a flask of the undertow that I purchased for 499g and then sold for 902g – but I only sold one out of the 4 I bought so far. Bigger sales but smaller profits include ink, battle potion of intellect, leather, and silk. These are not consumables, but are still money in the bank.
Problem is of course you’re not the only person out there doing this and the market can get flooded. Someone put up 28 stacks of 200 for well under the normal cost and there’s no way I want to try to sell all of that off unless I can craft it into something that would actually move. It really does take a bit of time and effort to learn your server, but once you get there the rewards are certainly worth it.