When I started in Crazy Quilting in 1997, in Sacramento, I had a dozen-literally-thrift stores in my working territory...I was in advertising sales at the time...and I would hit a thift store almost everyday. Since there were so many, I guess, their prices were very competitive. I could buy a full satin or velvet gown for $4 or $5. I would also buy silk blouses. And gowns with rinestones, lace or beautiful buttons were keepers. I once bought a dress, kept the mink that bordered the hem, and donated it back to the thrift store! Most crazies have depended on thrift stores for the fancy fabrics, because they are extremely expensive in the fabric stores, and almost never can be found in fat quarters! Brocades, moires, and Japnese fabrics were also great finds. I think I have enough fabric now that I don't buy as much...and now in Idaho, the two thrift stores are a lot more expensive than I used to shop in Sacto.
On my site:
http://www.flickr.com/photos/52086995@N00/
I have a work in progress that is made mostly of cottons, from Judith Baker Montano's collection which are very rich in color. The Robert Kaufman fabrics she promotes are a silk/cotton combination and have a wonder sheen to them.