I found nothing in Florence or Rome when I was there in 2008. And I specifically looked. I did find one fabric shop in Rome that had some cotton on the second floor, buried. It was extremely expensive (over 100 Euro/meter and not what I would consider putting into a quilt.
Same thing in Paris although I did find one quilt shop run by an American that was selling the same fabrics we can get here for about 19 Euro/meter.
I think a trip to Europe is not the time to plan on quilt shop hopping. :)