I'm a Tailor, but so far I make most of my money on Stroma Wash, Oil, and Resin. Had to buy a level 10 scholar recipe book I think. it was the highest level I could use (thought 9 would be but, hmm). Don't bother with the Apothecary book, it'll cost you twice the candles to make it with that recipe.
If I harvest my own tuber strands, then all I need to buy is candles and water (14c + 18c = 32c). And with Stroma Wash, if you make a normal item, you get *3* washes, and if you make pristine, you get 4 washes! Can't beat a deal like that when you get multiple quantity from one crafting session.
Yeah, just monitor the market and find your niche. I often buy out people selling Wash for cheaper than me, so I can maintain the price I feel is fair for the item, and it gets me all the sells ;).
I average about 60s - 130s a day, just leaving my merchant board open selling the stuff. Wash for 1s95c, oil and resin for 95c. but it could vary based on supply and demand. Good luck!