That would depend entirely on your server. Back before merger, when my mains were on Toxxulia, I made a very good living with a tailor, a woodworker and a provie. In fact, sales room was so valuable, I used to vendor all the drops I got because I could make much more money by saving the boxes for my tailored goods, (and food and weapons).
After moving to Najena, I found that dropped goods sold much better than my crafted leather and cloth, there was almost no market for wooden weapons and food/drink were fairly cheap. Could be the timing (or my current tiers), or it could be the dynamics of the local economy. Whatever the case, I don't think there is one be all, end all craft for making a great living. If there was EVERYONE would be in it!
My recommendation would be to research the broker screen for a while, charting what is selling locally and what is not. When you find the holes, it should give you an idea of whether or not a sage will work for you.