I've gotten a lot of quality fabrics lately at estate sales. I read the listings on
www.estatesales.net and if they list crafty kinds of things, I go early. I've gotten a lot of 2yd pieces for $1..... bring them home and wash them. One sale I went to must have had 100 2yd pieces.
I love the thrift shop shirts.... again, check for fiber content. I quilted a lovely quilt for a cousin that was all kinds of blue shirting fabrics.... it was really pretty.