Each weapon is sold at a 10% markup + charisma + rush. This means each copper ingot used to make a weapon that is sold nets you $1 profit, so the early game goes really slowly. Ignoring the cost of everything else, you would need to sell 500 copper ingots worth of stuff to get a single tin bar. The other stuff is where you make most of your money early game.
Once you get to tin, things pick up a bit. Each ingot is now giving you a $50 profit, so only 20 ingots to get to iron. Once you get there, it's only 50 Iron to adelite, 20 adelite to mythril, 50 mythril to adamantine and 20 adamantine to titanium. Of course, by the time you've got to the higher tiers, your customers will be really impatient making it hard to meet their demands.