1/ Friend with a crafter and ask him to make crafted gears lv 50 for Battle Gears or lv 35-40/50 Crafting gears with your mats. Go out and SB. You will either tons of Gil or double your profit, never be a loss.
2/ If you already have 1 50 Crafting class, do Ixali daily beast tribe to get the Knots. Use them to trade for Sealant at the cost of 8 Knots, then sell them. Each goes for over 100k at the moment.
3/ Easiest way is to buy an item during the weekend and sell it after the rest for a higher price (with fee included) and profit. Though, this is just a small change comparing to the others two methods.