Yes, Lets say you buy 10k Ess for 300k so you have 400 trades, at 2k each trade you will need to bring 800k gp, once you craft all the ess into airs you should have 60k airs, if you sell these at 20 each you will get 1.2m. Now it cost you 1.1m to buy the ess and the trades. You just made 100k, You could always makes another 100k if you bought the ess 20 each, but thats hard to do in bulk. Also you could try to trade 1.5keach trade if there are few to non-crafters there, but you can only do this some times.