Because the materials in a gown or an iron pot were so valuable, late medieval and early modern cities had all kinds of trades which specialized in repairing used goods, and all kinds of people who bought and resold things people did not need right now like pawn shops today. If a king wanted to equip an army, one of his household made some inquiries and a merchant would buy up all the used kit available and sell it to the king (Francesco di Marco Datini was in this business, and in Poland they still call pawn shops Lombards). Cobblers repaired shoes, fripperers remade clothing, and tinkers did small metalwork. There was a trendy term for this in the Silicon Valley crowd a few years ago, but its a very old practice.
For story purposes, these trades give good opportunities for characters to meet or see traces of each other; they also served as fences, in 16th century Seville the fripperers had to display purchases near the door of their shop for a certain period before they could re-dye, re-line, or otherwise alter it so that anyone who was burgled would have a fair chance to recognize their clothing.
They might be the people to ask for any special modifications to common objects which monster-hunters or world-walkers need.