Actually to verify ezcosplay.com authenticity is very easy. Since they have the facebook page: http://www.facebook.com/ezcosplaycostumes
.. Just go their facebook page and see how's their real customers or reviewers response their reply. Don't take the number of LIKES in facebook as account because those LIKES in facebook can be bought easily.
Some facebook page have 10,000 LIKES but every single post in their page has very few comments and some even 0. So it is quite strange rite?
That's how I check the authenticity of a business website before i purchase. One thing for sure, customer do not lie and bad things about that company do spread very fast.