Students from the previous years marked the following appartments as the most popular ones:

Corvin Plaza Apartments - http://corvinbp.com/

GoodMo House - https://goodmohouse.com/

Bell Appartmants - https://shorttermrentalsbudapest.com/

Airbnb accommodations may also be a good option in Budapest.

A unique accommodation possibility - 15 minutes by walk from the University Campus
Our previous Summer School students liked this idea a lot, as they could socialize much better and could create a community very soon.
Brief description:
The „Akacfa Street” unit is 280 sqm consisting of 6 separate rooms, three bathrooms, a kitchen to share, a living room and two big terraces.
Maximum occupancy is 16 people, each room is double.
The rental period is between 19th June and 14th July, 2020

Prices:
in case of 10 guests: 280€/guest/month (this advantageous price refers to shared rooms: 2 students share a room)
in case of more students - max. 16 -, the price will be somewhat less