The cost, density and resistivity of copper, steel and aluminium

Copper:
cost = 2.13 usd/lb , resistivity =   1.7×10⁻⁸ ohm meter, density: 8.96 g/cm³

steel:
cost = 17 usd/tonne  , resistivity = 10×100×10⁻⁸ ohm meter, density: 7.60  g/cm³

aluminium:
cost =  0.67usd/lb, resistivity = 3.2×10⁻⁸ ohm meter, density: 2.70  g/cm³

Electoral current force mechanical advantage if the wheel and axle is 2 n and the output force is 20 n