Sure, but that means the Roman cost would be even cheaper. If silver was cheaper in Roman times, and iron was 1/300th the cost, then the Roman nail becomes even

Sure, but that means the Roman cost would be even cheaper. If silver was cheaper in Roman times, and iron was 1/300th the cost, then the Roman nail becomes even cheaper (which doesn't make sense) I'm not sure what the hourly rate for a day laborer would be. $20/hr? I think the real issues with this calculation are the idea someone can crank out 2,300 nails / hour. I think 1 per minute (sustained) seems much more reasonable. That makes the labor cost 40x more. And maybe it would be a semi-skilled occupation, so $20/hr or $40/hr makes more sense. So now the labor cost is 150x more.