look online at Hotel des Grandes Ecoles: Average price*: $124 (€95)

75 rue du Cardinal Lemoine, Paris 75005,
about 2 blocks from the nearest metro and 1-2 blocks from a 4-5 block long main street full of shops, cafes and resaurants. ask for a room in the annex that overlooks the garden. no ac so fine for sept to april. very charming and one of the great bargains in that part of paris. the hotel sits far back from the street and is quiet as a churchmouse.

ttt

It's been a number of years since I was there but Hôtel de l'Avenir should suit you. Great location, around the corner from Jardin du Luxembourg and halfway between Montparnasse and St-Michel. The website has some nice links.
http://tinyurl.com/3ycktt

Oops, just noticed that this is an old thread.

tabernash, Where did you stay? How was it? When? How much?

I stayed at Moderne St. Germain when I was in Paris in Nov 2003. The location in the Latin Quarter was great. It's close to the university so they have a lot of bookstores, cafes and restaurants around. Employees were friendly and helpful. They may have remodeled since I was there because the pictures on their website look more modern than what I remember the hotel to be. Rooms and bathrooms are really small but clean. Elevator is really small... barely fit me with my 2 suitcases. Breakfast was good. The window and walls are pretty thin though (not great at keeping noise out), but it wasn't too bad.

Oops, just noticed this was an old thread myself. I guess I should check the dates before I start writing.