Yeah TFT (tokyo fashion town) is also in Odaiba. It often takes place at the same time as Comiket and is just another building for cosplayers to take pictures in.
Off hand I can just think of Dream Party in October, the Tokyo Game Show, and winter Comiket.
Some events charge 5-800 yen to register your camera. But they won't let you register a video camera. That's one downside to Japanese cosplay events. They often don't allow video recording and many cosplayers won't let you take videos of their costumes.
So you either have to have pre-set up plans, surreptitiously sneak in your camera and hope that cosplayers are willing to shoot with you. And if you don't know Japanese...any kind of directing can be tough.
But I won't give up!