This little initial superhero cape is not a Halloween costume idea (although it certainly could be and might be if I don't get my act together LOL) but more a fun idea for every day play.
My mom got Leo this awesome Super "L" cape for his 3rd birthday. He loves it. Has been running in it, jumping in it, knocking his brother over in it, sleeping in it. What a great idea!
My mom found this Little Hero Initial Cape ($45) at Mahar Drygoods (they also have Little Hero birthday capes with ages and Little Hero capes with cute symbols). However, I know you crafty mamas could probably whip one up in no time.
Another more affordable cape option is the Superhero Starter Kit ($10.17).