Yes, some favorite thrift stores. And especially church
yard sales/ rummage sales. You can get some real bargains
at such sales.
And I'll admit that sometimes I cut extra large garments down
to fit me!! Some of the older clothing have very good to
excellent fabrics that are never seen any more. Not quilting
related, but one of my very favorite "out to eat" dresses is
one I cut down from one of my aunt's evening dresses...and
I'm 76 so that makes it OLD. It's a thick jersey I think, cream
with huge red flowers and just as large, fancy paisley prints in
it. I love it and have for many years. Now one of my granddaughters is hinting strongly for it, and it fits her!!