I consider staying in Paris for relatively longer (10 to 12 weeks) next year.

Since the hotel is expensive, I usually use AirBnB, but even AirBnB costs about €45 per night, which is still quite expensive.

I believe there should be some cheaper alternatives, like renting a room, since AirBnB is targeted for travelers staying for a few days to a few weeks, so if you keep staying for a few months, it would not be comparatively cheap enough any more.

So, is it possible to rent a room in Paris as a traveler (i.e. no valid visa), for only 10 to 12 weeks? Otherwise, what kind of options are available to stay in the center of Paris, possibly for less than or equal to €35?

By “the center of Paris”, I consider 1st, 2nd, 7th, and 8th arrondissements. And I only consider any accommodations I have my own room in.