That would bring it down to only ~7 years of labor if we call it 1 min per nail, assuming that you're already working from prepared bar stock. Still a significant expenditure of skilled labor!
As I understand it, nail making was largely unchanged from the Roman era. One would have to adjust for work hours which differed in the past than today for those, but it like it would take someone 2 years to produce that number working modern hours, though likely less than 1 in the era they were produced.
[1] https://www.mortiseandtenonmag.com/blogs/blog/issue-15-t-o-c...
[2] https://www.bournheath-pc.gov.uk/about-bournheath/bournheath...
[3] https://www.adamsmithworks.org/documents/chapter-1-of-the-di...
Quick google suggests iron was 1/300 the value of silver in the Roman empire, so if we say $40/oz, that makes an oz of iron = $0.13.
a 10-penny nail is about 0.2oz, so $0.026/nail.
$0.026 + 0.004 = $0.03/nail.
If I go to home depot, 1lb / ~80 10-penny nails would cost me $9, or $0.11.
So, astoundingly, it was cheaper in the Roman empire to buy nails(??). That doesn't seem right... Modern nails are different material (galvanized / zinc coated), but still.
I can't find the price of nails in roman times, but 300 years ago it was around a buck a nail.
https://www.nber.org/digest/202203/tracking-price-nails-1695
It says 200/hr, 3,000/day and 2,300/day.
I would use the salary for a day labor instead. Like if I spend my salary for a day on just nails, vs how many nails a smith could make for the same number of working hours.
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.