i am assuming you checked the bazaar? if so they don't come up often what works for me most of the time is just to keep refreshing and buy them when they come up, it may take some time, but there is always somebody selling or making reagents available just spend a while looking and they will come up eventually.
You can find scrap iron in Marleybone. Go to Regents Square and run the perimeter, a mount will speed things up.Scrap iron and mist wood I find often. Look in the corners, do a lap and change realms and repeat. Try realms that are not crowded.
I think east and west counterweights are the best place to get it. Just go into the dungeon, get the scrap iron from the first floor (no fighting required) and then leave. I believe you have to switch realms so that the dungeon resets, but I don't remember for sure if you have to switch realms before going back in. Good luck!
check the shop in wizard city everyday. i got like 50 of them there and they are in marleybone and i think you can make scrap iron but it is easy to find
Also if you have a membership and a friend that has acess in celestia go to the crafter and you can get the transmute scrap iron I think you should ckeck it out.
