No money in iron any more. On Figaro, nuggets are now going for as low as 350gil where they used to go for as high as 1500gil. Plus, silver is the BSM grind for 45-50, so it's becoming more in demand.

As dangerous an area as it is, Treespeak is the place to go for this stuff. And gives good leveling. Two notches from the top of your slider tends to work well - you'll also get gemstones.

On an unrelated matter, get yourself a Gridanian Doublet if you're grinding. For leves, wear the Lominsan Doublet Vest. +20 to Output or Gathering respectively from Rank 25.
Gridanian Doublet is best output in the game. Jerkins don't get better than the Lominsan Doublet Vest till the much higher ranks. Love that company gear.