Apothecary.

The Apothecary sells potions and potion ingredients. The shop is "fascinating" despite its very bad smell — a mixture of bad eggs and rotten cabbage. The inside includes barrels of slimy stuff on the floor; jars of herbs, dried roots and bright powders on the shelves; and bundles of feathers, strings of fangs and snarled claws hanging from the ceiling. Some of the ingredients available are silver unicorn horns (for twenty-one Galleons each) and glittery-black beetle eyes (five Knuts a scoop.)