Link arrived just after a Goron race had ended. He recognized the winner, although he knew the goron wouldn't remember him. "Excuse me, sir."
"Yes, human?"
"Congratulations on winning the race! Um, did you get any gold dust as your prize? Oh, great! Is there anything I can trade you for it?"
"Well, maybe with 200 rupees or so, I could bear to part with my prize."
Link had exactly 200 rupees, and he gave them to him in exchange for the gold powder. "Now it's just the metal. Skull kid, did Solro say anything about how much of the metal he required?"
---------------------------
Once he saw the human, the Mask Salesman stepped back into the shadows and headed back to the surface level of the Clock Tower. Best to avoid contact for now, he decided.