Ashley Payne of Freehold, N.J., and Matthew Orbach of Brooklyn, N.Y., were up to their necks in Balzacs at the 88th annual Toy Fair, held recently in New York City. Decorated Balzac balloon balls, introduced by Milton Bradley, can be filled with air, water, rice or even coins. The balls were but one of scores of new product lines promoted by manufacturers and distributors at the fair.