The new Rainbow/Ramie/Archaeoskin/Dragonskin glamours that came out with 3.1 cost pennies to make and sell for anywhere from 30-70k each on Gilgamesh. Several weeks later and I still have trouble keeping my retainer stocked with them. Also, the Sky Pirate gear made me the easiest 15 million gil I've ever earned in less than a week and even though the price has come down, it's still a great money maker. There's also a pair of new recipes that have made the farming of a certain expensive material very, VERY cheap and easy and I'm currently making a fortune off of it.
If for some reason you can't craft over level 50, the Zodiac quest items (perfect vellum, etc.) sell for an almost ludicrous amount now that SE has nerfed the old relic quests into the ground. Huge influx of people doing their relics vs. not very many people who bother with 2.x crafts.
There is always gil to be made. There are lazy people everywhere in this game and they are more than happy to give you their money.