hostel or inexpensive paris recommendations??

Hi, my friend and I (both 27 yr. old females) are going to Paris Sept. 30th-Oct. 10th and I need some recommendations on where to stay on a budget... Any help would be appreciated, there are so many hostels and hotels to choose from, which would be a better deal? I know Hostels are about 20-30/night per person and include some sort of breakfast, and some hotels are 60-70/night.
Help!!

Sarah