It's all going to boil down to buying ore/bars from a blacksmith...so you a blacksmith...can blacksmith. Whether that's iron, steel, orchish, elven materials or whatever. It would be like buying hamburgers from a competitor and then making the burgers and selling them at your burger place or funnier yet, back to the place you bought the burgers from.
As several of us have pointed out, there's nothing requiring people to do that, outside of an obsessive need to powerlevel, min/max, powergame. Many of us have leveled Smithing off the materials we found in the world.
Which has a multitude of advantages.... trying to find more stuff is yet more reason to explore caves/mines/mountains, it gives a slower progression to the skill so that you don't end up with the whole "OMG, I got Smithing to 100 at level 12! I'm either overpowered (my gear squishes everything) or underpowered (all the enemies are too high level for my tiny combat abilities)!", etc.

