I'd like to know the ball park cost in time, and/or money for making a simple wrench.
For example a typical 14 piece set weighs 2.6lbs, and sells for $22. The cost per wrench is $1.57 and the lbs per wrench is 0.185, so I used the steel cost of 30 cents per lbs, and came up with a cost 5.5 cents for the steel. I looked it up and it cost only 2 or 3 cents of energy per pound to melt steel, so the melting is a very small cost. So to me it looks like there's quite a bit of profit margin on a wrench. I know I left out the nicle plating.
I have no direct experience with this, but aren't wrenches typically drop-forged instead of melted and cast (or machined from bar stock)?
If so, then wouldn't the calculation involve allocating capital costs for the forge and tooling as well as construction costs and labor across some anticipated production volume? I don't think that you're going to get a meaningful figure by simply calculating a supposed raw material cost.