Gelateria KmZero is located in the Porta Lodovica neighbourhood, close to the Bocconi University in Milan. It's not a popular spot in the city, so you won't find that much queue as it's also not in a touristy area.
It's one of my favourite gelateria in the city and I often go here for a delicious gelato.
Prices are around 3/5€ depending on the size. It's great quality and would highly recommend it.