I originally posted this in general, but then realized this might be a more appropriate place to do so. I've recently started using online thrift stores to re-do my wardrobe and I've had a lot of luck at these two...
Thred Up has really nice stuff & you can search by brand, size, etc. If you use this link you get $10 to spend (and so do I):
http://www.thredup.com/r/OJNWKFSchoola is a similar format, but 40 percent of your purchase profit goes to a high need school. I'm a teacher so I've got to support this one! The link gives you $20 to spend (and I get 20 too).
https://www.schoola.com/stitch?ref=cp-3Xaxf00PX