I have a Hampton Bay ceiling fan - model CC 52HD. It currently has a light kit attached to it and I'd like to remove it, but need the "cap" that should fit over where the light kit currently is attached. Anyone know where I can find one of these? Are they standard?

Yes, they're pretty standard. Just measure it's diameter. It should be 3 or 4 inches. Lowe's and Home Depot both carry them.