Concerning the accommodation in Medellin, there is something for everyone. There are several possibilities, from hostels and host families to private apartments or studios. It goes without saying that the prices also have a quite big price range.
If you have a smaller budget you could think of a host family or hostel. The advantage of a host family is that you become more involved in the Colombian culture and often only Spanish is spoken, which will speed up your learning process. In some host families, meals are included in the price, others do not have this or it is on request.
Staying in a hostel is also a good option. You can opt for a dorm or a private room. The advantage of this is that you will meet many international people who, like you, want to have a great time.
Find here a clear indication of the accommodation costs.