No, it takes 2coal and 1 iron to make a bar. it takes 5 bars to make a plate body, so 100 for iron, and 200 for each coal is 500 per bar. 5 bars is 2500 gp + a nat so its around 2800gp per plate, with an alch of 1200, you lose 1600 gp per alch. DO NOT MAKE YOUR OWN PLATES ! and you could get green bodies for 4400