If you belong to Costco or BJs they've got a pretty good selection right now for little kids (don't know what age you're looking for).

Can't speak for the quality (I think they sell a lot of different brands), but yoyo.com (owned by diapers.com, and I think ultimately, Amazon.com) has a big selection.

Too rich for my blood, but if you're willing to spend that much, I've heard good things about Chasing Fireflies:

http://www.chasing-fireflies.com/costumes/departments/46/

Spirit Halloween on Rt 7 in Tysons. Lots of costumes AND a lot of fun (and by that I mean "scary!") props and mannequins and things. It's fun just to look around in there and get in the Halloween mood.

Party city.

PP here. Kohls is giving 15% off for Halloween costumes with the code that is right up front in their website, plus they are having a big sale thru tomorrow.

kohls.com with the 15% off code that runs through tomorrow. I'd post the code, but I left it at home.

Not cheap/great quality: chasing fireflies.

Decent quality, limited selection: Old Navy.

I dunno, but do not go to Night Dreams in Tyson's. DH and I went there 1 or 2 Halloweens ago, since it came up in our internet search for Halloween costumes. Somehow the name didn't clue us in as to what it really was - ha!

Any good suggestions for places to order Halloween costumes? We tried costume express or something last year and the costume was flimsy and very poorly made. I don't want to spend $80, but I would like to find somewhere with a higher quality product for our elementary aged kids. Suggestions? I think we'd prefer to order on-line.