I will reveal my newest project or at least some of my ideas and inspirations for my next shop. I´m planning a Borgin and Burkes shop.
Description from the Harry Potter Lexicon: Just around the corner from Diagon Alley lies a dark, twisting alleyway devoted to the Dark Arts: Knockturn Alley. Some way down Knockturn Alley at number 13B lies Borgin & Burkes, the most notorious of the alley's shops, which specializes in "objects with unusual and powerful properties", and particularly items that are both "unusual and ancient". The shop is quite large, dusty, and dimly lit, with a large stone fireplace, and is known to be frequented by families like the Malfoys. Its proprietors, Mr. Borgin and Caractacus Burke, are smooth talkers known to buy magical objects for much less than they're worth, and sell them for far more. From the shops and the street vendors one can purchase, among other things, shrunken heads, poisonous candles, human-looking fingernails, and Flesh-Eating Slug Repellent.
Photos found on the internet for inspiration.