The cheapest way imagined by me, is to use automation to extract goodies from psyche using solar power or nuclear fission for any further-out mining bodies, or use solar power sats to collect and beam the electricity via microwave, laser, or maser, to wherever the manufacturing will occur? NEO or L2, or tween Mars and Jupiter (asteroid belt) and then send the ingots back to earth orbit. (nuke rockets or photon sails for the return journey
) Getting the goodies back on earth to my mind could be done by simply using automated shuttle craft (X-37 tech) and land at air ports. Other proposals would be to use parachute landing of the valuables in the Indian, Atlantic, and Pacific. Last, of course are space (Artsunatov-Clarke) elevators manufactured from graphene composites (coal) that rise up some 23000 miles. How likely is that?
Don't ask! Closer in is the Moon which has collected deposits of water and minerals for the last 4.5 billion years. A primo source for mining, radio astronomy, tourism, etc.