Three businesses cashing in on discount merchandise including the popular Home Shopping Network head Inc magazine's 10th annual list of the 100 fastest-growing small public companies.

Two Utah firms, Bonneville Pacific, Salt Lake City, and Ballard Medical Products, Midvale, were among Inc's top 20 rapidly expanding small businesses in the nation. Bonneville develops electrical cogeneration and hydropower plants.Entertainment Marketing of Houston, Texas, topped the list with a 38,763 percent increase in net sales or total revenues between 1983 and 1987, the magazine said.

The company's sales jumped from $226,000 in 1983 to $87.8 million in 1987. Its number of employees increased from 4 to 175 in the same period, while net income increased from $6,000 to $3.2 million.

Ranked second was Home Shopping Network, of Clearwater, Fla., a televised specialty retailer that sells jewelry, knickknacks and miscellaneous items to viewers who call in. Sales of $582 million in 1987 compared to $3.6 million in 1983.

Warehouse Club of Skokie, Ill., was third on the list with a 15,469 percent increase in net sales between 1983 and 1987. The company, founded in 1982,.operates a chain of warehouse stores.

To make the list, a company must be an independent business, publicly held before the end of fiscal year 1987 with an operating-sales history of at least five years. A firm's 1987 sales must have exceeded sales during the previous year and its 1983 sales must have reached at least $100,000 but be no more than $25 million.

The list's top 20 fastest growing small public companies are Entertainment Marketing, Houston, Texas; Home Shopping Network, Clearwater, Fla.; Warehouse Club, Skokie, Ill.; Care Plus, Miami, Fla.; Domain Technology, Milpitas, Calif.; Osicom Technologies, Rockaway, N.J.; Sahlen & Assoc.; Deerfield Beach, Fla.; Gateway Communications, Irvine, Calif.; Linear Technology, Milpitas, Calif; Vipont Pharmaceuticals, Fort Collins, Colo.; Harken Oil & Gas, Bedford, Texas; Bonneville Pacific, Salt Lake City, Utah; Excelan, San Jose, Calif; National Healthcare, Atlanta; General Pharmaceuticals, Berkeley, Calif.; Encore Computer, Marlboro, Mass.; Sun Microsystems, Mountain View, Calif.; Ballard Medical Products, Midvale, Utah; Catalyst Energy, New York; and Businessland, San Jose, Calif.