Two years ago, I stayed at Hotel Loiret in the 4th (Marais), just steps from Hotel de Ville (and a metro stop).

A room with double bed and bathroom started at 60€. Some rooms were different sizes, so you may be able to get an even bigger one and still stay under the 80€ mark. It was a budget hotel, but it was clean and quaint. I even got more bang for my buck by staying in a room for 45€ with the bathroom down the hall!

We easily walked to Notre Dame, Ilse St. Louis and Place des Vosges. We spent a lot of time just exploring our neighborhood. The Marais is was a great area to stay in and we can't believe that we stayed so centrally for so little!

Try :

http://www.paris35.com/

Well I reserved Hôtel Bastille de Launay as it had room. Everyone was certainly right about the hotels/apartments filling up fast! It was pointed out to me that I will be there at Rugby World Cup season which ratchetted it up I'm sure. I will keep surfing around though as I can cancel if necessary or advisable.

I am now trying to find a place in Venice but only for one night and it to seems booked. I was also looking at the trains from Venice to Paris and am feeling a little stupid as the site for Trenitalia is completely in Italian and so not to sure how to deal with that. Looked into the posibility of flying from Venice to Paris and Ryanair offers a really cheap flight.
Any thoughts/suggestions?

Here's the English version of the Italy train site:
http://www.trenitalia.it/en/index.html

Can't help with a hotel in Venice.

MyAir also offers a cheap flight between Paris and Venice, and with better airports.

OK I now have it narrowed down to Hôtel Bastille de Launay in the Bastille disrict and Tourisme Hotel in Eiffel Tower area. Thoughts?

I have decided that I will spend the day in Venice but will then take a night train to Paris so won't need to get a hotel in Venice.

Thanks cls2paris for the english version. Still trying to navigate to figure out prices etc. This site has reduced me to a no mind! Should I make reservation before I go or wait until I'm in Italy?

Definitely the Bastille area!

Not sure of the current cost, but here's an article about staying at the Hotel Dieu Hospital next to Notre Dame which has rental rooms on the top floor. Sounds like a unique experience.

http://query.nytimes.com/gst/fullpag...amp;sec=travel

Also, there's the Maison Zen which has rooms for rent
http://maisonzen.com/