I will be studying in Paris for the next 6 months. I am trying to find a nice apartment, but the rental agencies ask me to pay 1 to 2 months of rent in advance for their services, then there is also the guarantee landlords asks. So I think this is all very expensive. I tried a free site pap.fr where you can directly discuss with the owners. They asked my payslips of the last 3 months, which is fine, but then most say that they already rented the place to someone else. I earned quite a good salary. So is it because I am foreigner, I also do not speak very well French, so maybe they prefer local people. Does anyone know an agency that does not charge huge fees and can find a long term home for a foreigner in Paris?
Students in France usually rent for one year so if you go to an agency for only 6 month they simply won't be interested nor would landlords. There are however many solutions for students and temporary accommodations.
I would recommend that you contact students in your own country who have been in Paris. They might have contacts. Alternatively look on your embassy website or get in touch with expatriate from your country in Paris who can to be very helpful with their compatriots.
On a side note, there are countries where the practice is to ask for a year rental in advance.
Once you get past the first page, you can modify your search by panning/zooming the map. Paris, France showed thousands of listings. Limited price to US$ 45/night or less and it was still over a thousand. Zoom in till only four metro stops from the Louvre are showing and had fourteen available mid-January for US$ 45/night.
Some can be "seedy" but if you study the listings and testimonials, with that many choices, you can find something good. Best of those fourteen (in my opinion) was US$ 33/night or US$933/month (plus a fee for AirBNB).
Another option: WarmShowers.org, BeWelcome.org. Find someone local to stay with for a few days who knows the area and can help you find a good deal.
thanks for all your comments ! In the end I followed the advice to ask someone of my university in my home country who stayed in Paris. He recommended me a site that he used to find his rental apartment: http://www.paris-start.com They really did not charge a lot for their help, compared to the agencies I visited and they helped me even with the translations and everything. Just signed the contract for my furnished studio ! :)