An option that I've not seen spoken of is the Daily Hunts.

By these I mean the hunt sheets you pick up that are level 1, 2, 3. Each has five regular mobs to find and kill on it. With each kill you get 1K to 2500 Gil, exp, and Centuro's. Do all 15 and it's about 25K or so I think. Each expansion has them, so you can do a ton a day, and the income is nice. It just takes time.

Doing the Beast tribes is also a slow but steady income source. You get a thousand or so Gil, a tribe token, some poetics and exp for each you do. It adds up.

It's no hand over fist Gil, but do it for a week or two and its a few 100K and you get other things also.