There are many places online that offer fairy costumes for children. On eof the best places to find these costumes is the website spirithalloweenstore.com.
You can find hundreds of good quality costumes at: "http://www.mrcostumes.com/". Make your child happy with the variety of costumes this website has to offer.
To find wizard of oz costumes, you may search their costumes on their own website. Depending on where you live, if you have a Target store around you, you may want to try to visit their store and find the costumes.
http://costumeideazone.com/ This website has many great costumes available to the public. I am sure that you will find exactly what you are looking for here !
There is an offical Alice in Wonderland website for halloween costumes! http://www.buyaliceinwonderlandcostumes.com/. You can also find Alice in Wonderland costumes in stores at Target!
Here is a website that offers kids, teens, and adults X-men costumes: http://www.costumecraze.com/Superhero-Costumes-Xmen.html. This website offers X-men costumes exclusively: http://xmencostumes.net/.
One can find videos of scary people in Halloween costumes on the website YouTube. The sites has tons of videos of people wearing scary videos and even tutorials on how to make the costumes.
You can find costumes pretty much any dance website. I suggest Curtain Call. They have a wide variety of styles. https://curtaincallcostumes.com/about-us.php
i think that the pest place could be on Party City website
There are stores dedicated to costumes, like Matteo Party. But any costumes, including children's hambuglar costumes, can be found on shopping website like Amazon and eBay.
The Partydelights website is one of the best places in the UK to find virtualy any costumes to meet your party needs including a very good range of Wizard of Oz costumes suitable for both kids and adults alike.
The website http://www.officialstarwarscostumes.com/ has a huge selection of Star Wars costumes availible for purchase. They offer a variety of sizes even down to baby.