I read your comment on the style video, to me Cassie's sailor outfit looks like a dancing outfit, like the sailor ones they use in scottish highland dancing. For a sailors hornpipe.
I've found a link for you:
http://stepintime.bpweb.net/hornpipe-outfit-adult-p-44.html?zenid=b49c8dc2cfd910aa60dd96f085208447
