Budget 100-150 euros/night, any recommendations?
Steve,
I would recommend Hostel Archi Rossi. In addition to the typical dorms, they also have private rooms. We liked the location and the amenities.
Sharon
Try the Relais Tiffany. It is BEAUTIFUL and not far from the Santa Maria Novella staion.
http://relais-tiffany-firenze.com/
We enjoyed Soggiorno Battistero, a B & B on the Piazza San Giovanni. Most rooms (not all!) have a direct view of the Duomo and Baptistery from the third floor (American 4th) , and it's in your price range. Very centrally located, a lively area until midnight and sometimes later, but there are dual pane windows and heavy wood interior shutters in the rooms. A great place.