I usually sing praises about thredup.com to everyone I know... I LOVE that its used clothing (great for environment and budget) and that I can shop online, instead of having to drag my kid into a store and then "hunt" for clothes for her. Their prices seem pretty good to me and the quality I've received has been awesome (they gave me a shirt for free once because it had the tiniest bleach stain that I would never had seen had they not put a sticker on it!). I will continue to buy from them (just placed an order yesterday!)
I have been disappointed with the selling side of their business though. I have sent in 4-5 bags of clothing and only received less than $10 total! I would have just donated the cloths anyway, but I had hoped to make more, so I could buy more. I will most likely not sell to them again in the future. I did sell some of my (women's) clothes and made $60, which was much better. They can sell adult clothing for more, so your payout on these items is also more. Its easy for me to order a bad, stuff it and put on my doorstep for the UPS guy to pick up... but with the kids clothing payout being so little, will most likely not do that again.