10g on 100g investment in 24 hours can be done with just by-hand analysis on gw2spidy.com. The simple buy low/sell high method can get you your 10% return rate per 24 market hours, I'd bet. Just be careful and learn the weekend cadence: get your goods up before the server matchups happen. For the most part, buy during low population hours, sell during high.
Nothing will beat good speculation on in-game events, however.
Also, when demand shoots up, I've found that most often, it peaks quickly. There are a lot of players in the game, and they'll figure out what new thing they want quickly. The sellers are usually slower to react, so the demand rockets, then gradually declines. Not always, of course. So don't ever sit on goods that can turn a healthy profit. It is possible that demand goes up, but I find more often, you'll miss whatever window was there if you sit on anything. Plus, there's always another market to capitalize on
Another important point: experiment. Relatively obvious or simple ideas often do make nice income, because most people aren't working hard to maximum virtual gold coins
We're all (hopefully) playing for fun, so you can make money off of people's casual nature by expecting them to trade gold for time (e.g. crafters buying parts for more than they cost to craft because they don't want to spend the time to double-check). In other-words, if playing the TP is fun for you, you're in the minority, and the majority will pay you gold to shave time off of tasks they don't enjoy.
I've taken that idea to the next level: for my current method, which is so far doing very well compared to my previous methods, I basically observed my own behavior as a casual TP trader, then came up with a way to turn a profit on someone like me. In other words, the more people on gw2spidy.com, the more quickly I make money
They'll make money, too, they'll just end up sharing some of it with me. In order to recreate my method, they'll need to be decent programmers at a minimum, plus have a couple of key insights into how casual traders think. Not to say that my method is ideal, but I do think it is unique, which keeps it viable. We'll see for how long! P.S. my method is low-risk AND not in the least exploitative. You don't need to be a crazy market analyst with market prediction skills or a cheater to make a really good, sustained income.
Edited by Humungous, 30 November 2012 - 06:29 PM.