I was in Florence two summers ago with my partner, sister, and brother inlaw. We rented two rooms, shared bath, from Mossimo and Stefano at their apartment.

http://www.bearsandbreakfast.com/

The location is good. Just outsite the tourist area and easy walking distance to the major sites. Quiet, clean, and comfortable place, friendly guys. Better than some of the hotels I've stayed at in Florence and at a much better price.