I've seen it on an infrequent but consistent basis, and know of people who participate in cosplay parties on a regular basis. There are folks who make a living or a hobby out of dressing up as various superheroes and attending comic-cons, sci-fi conventions, and whatnot.
And never mind things LIKE comic-cons and anime conventions, where damn near half of the attendants, if not more, are dressed up in costumes. I once went to get some food and notices Ryu and Chun-Li in line behind me and was like "oh, it must be Anime Con time again". And I was right.