Cereal Marshmallows can help make your dream of a marshmallow-only cereal a reality. This site sells bulk bags of marshmallows that are exactly like the ones in your favorite cereals.
Cereal Marshmallows is a genius idea. I can think of no other place to get marshmallows from cereal except from this site. The market may not be big, but they have cornered it. Besides, adding marshmallows to almost any cereal improves its taste, as evidenced in the video above.