I shop yard sales, Goodwill and Salvation Army all of the time and find some great things to use. I do wash all of it.
If you have a place close by that sells fabric for curtains, etc and they have all of the samples to chose from....ask if you can have them or pay just a little for them. The fabric companies generally send reps in twice a year to weed out the discontinued fabric. Many shops throw them away. I have a lot of it and use it all the time.
A local upholstery shop saves me all of their scraps which are wonderful. A bit heavy for a quilt but perfect for a purse.