It's worth knowing some ballpark prices for various raw materials. Don't take these too literally—they're intended in the spirit of
High-Tech saying gas costs $1.50 per gallon. I didn't do anything fancy here, just Googled the prices of these alloys, converted 2004 dollars, and rounded off:
- Aluminum: $0.70/lb.
- Copper: $2.25/lb.
- Lead: $0.75/lb.
- Nickel: $3.90/lb.
- Steel: $0.20/lb.
- Tin: $7.00/lb.
- Ferrotitanium Alloy: $2.80/lb.
- Zinc: $1.05/lb.
These are fairly cheap compared to finished products. And commodity prices for lumber and plastics are even lower. This suggests labor costs will be a higher percentage of final costs than at lower tech levels. (Indeed, human civilization has gotten a lot more efficient at churning out iron and steel since the age of sail!)
For machines like guns, cars, and airplanes, I think the real question is to understand the minimum capital requirements for a supply chain, and what % of the wholesale cost that accounts for.