So, before I left for Rome I researched fabric stores and I found two promising possibilities. The first one was Azienda Tessile Romana and was a fairly normal fabric store, but with really high prices. I didn't find any fabric that knocked my socks off and I was always concerned about my luggage becoming over 50 lbs and having to pay $$$ so I didn't make a purchase.
The next store was Bassetti Tessuti and this place was intimidating as heck! It is absolutely stacked from floor to ceiling with fabric and each room features specific fabrics, ie. wool, silks, cottons, trims, etc. Since I speak no Italian, the employees were EXTREMELY haughty, no prices anywhere, so all I dared to do was to snap some photos with my flash off and me camera by my hip.
I did not purchase any fabric, again:( and in retrospect I really wish I would have overcome my sudden shyness and bought 2 yards of Liberty of London cotton fabric because the selection was HUGE and it would have weighed next to nothing. It makes me sad just to think about it.