Perhaps the word  apothecary  was being kind, as this was certainly a shop that delved into the less-than-legal side of potioneering. It rather reminded him of Borgin and Burkes and was down a darkened alleyway and three sets of stairs. The shop window was dusty, riddled with scrolls and potion ingredients. Draco had the pleasure of speaking with several unsavory characters in the market before finding one that could point him in the right direction. All cities, even clean, idealistic ones like Atlantis have a potion-master that  may or may not  dabble in the dark arts. 