With my previous success of using a shirt from a thrift store to give new life to my leather flats (which I wore today and had quite a number of people notice and compliment! :), I’ve been making it a point to scan the clothing sections in second hand stores for fabrics that jump out at me.
More surprisingly than not, thrift stores are a great place to find cheap fabrics for projects (and if you make a mistake, there’s no guilt hanging over your head :)
The trick is to not focus on the style of the shirt/skirt/jacket/whatever, but rather look at the print, quality/type of material, and the amount of usable material.
Take for example, the beaut I found on my latest thrift store run: