I just got back from GenCon, and got curious - any providers cosplay?

on their own websites that they do "role-playing" and many list the costumes or outfits they already have in their wardrobe.  Some of these will allow you to bring additional costumes providing they are new, and not "used."   I have also had regulars that would buy a new costume for a future session, and then I would reimburse her for it when I arrive.  This last one depends on whether you have seen them before and are reliable enough that you won't cancel after they advanced the money to buy the costume for your session.  Just do your homework.  If a lady has reviews, the reviewers will often mention cosplay in the body of the review, even though there is not a place to put it in the profile.  

It 's a nerd thing, but I would be Pikachu,

Yes Cosplay is lots of Fun!