3 days accomodation in Paris (and a beneficial suggestion)

Hii,

I am a Turkish erasmus student in Ljubljana/ Slovenia and planning a trip in January. Paris is also one of the cities I will visit. I am planning to stay there for 3 days (arriving on 26th january, departing on 29th) As you guess I need to arrange accomodation before arrival and I don't want to spend so much money, but I don't know so much about Paris that's why I need some help. Do you know a cheap and suitable place for me or I have another suggestion, for example when I have some visitors in my room in the dormitory they are coming with their own sleeping bags, so it is not a problem to find a bed, and if there is a volunter over there, I want to do the same. I mean if you could welcome me to your place I will come with my sleeping bag and of course regarding that you are also student, I am ready to pay some for this help. ( for example 20-25 euros for 3 nights, I just want to have a place but nothing else.) Even if there is no volunter for this suggestion I will be waiting for your help also for a hostel.
see you,