Alexis has investigated accommodation in Paris and found a very central hostel near the Louvre (http://www.bvjhotel.com/). This is from Wednesday night to Saturday night (so leaving on Sunday) and there is space for up to 27 people. It will cost around €105.
Please let I or Alexis know on Friday if you would be interested in staying at this location. We all stayed together last year in Essen and it was awesome!!