Because so many have asked, and I actually have experience with this one, I'm listing a hotel that I would suggest if you are coming to Paris but on a budget. A friend stayed there in February, and said it was perfect. The hotel is called the Hotel des Arts on the Rue Coypel in the 13th arrondissement of Paris, just off the Place d'Italie.
You can read about it here, and can reserve your room online.
Prices run from 49 euros/night (single) to 75 for a triple room. The rooms are charmingly decorated, with a full and very modern bathroom, a direct phone line, cable television and a fridge in the room. There is an elevator, and the staff speaks English (except the one older man that was there at 2 AM one night, but I was with her, so it was fine.) It's a Mom-n-Pop kind of place, so not cookie-cutter boring. She said that it was exactly what she needed.
The location is a block or so off the Place d'Italie, where the 5, 6 and 7 lines of the Metro have a station. Many buses also come through this area. There are lots of bakeries around to grab some breakfast, cafes, grocery stores, and even a big Centre Commerciale (mall) a short walk away. You can stroll up to the Latin Quarter in about 15 minutes, and walk up the Rue Mouffetard, picking up things to eat at the markets, butcher shops, and wine "caves". A short metro ride will take you just about anywhere in Paris, and the line 27 bus goes directly to the Louvre. Take the line 6 metro to go to the Eiffel Tower or Arc de Triomphe, the line 7 to go to Notre Dame or the Louvre (if you don't take the bus), line 6 to Montparnasse, line 5 up to near Sacre Coeur and Montmartre, or make connections to head elsewhere.
It's not a touristy area, so things are generally cheaper and there are less people trying to follow you around and sell you flashing crappy plastic Eiffel Towers for 5 euros. There are lots of local amenities (grocery stores, hardware, dry cleaning, laundromats, etc.) that are for people who live here, rather than lots of tourist shops. There are street markets nearby every day of the week, and lots of parks for sitting with a bottle of wine, loaf or bread and some cheese for an easy and inexpensive dinner. It's an area where you can practice your French, if you want, because not everyone speaks English here, but if they do they will want to practice their English with you, so let them. They don't get many opportunities in this part of Paris.
Enjoy your trip!