The Service Corps of Retired Executives (SCORE) is best known as a Small Business Administrationaffiliated organization offering free business advice. Now SCORE is also planning to sponsor a low-cost entrepreneurial networking organization. For $99 a year, anyone from the corner dry cleaner to the local manufacturer will be able to apply to be part of Opportunity Knocks (OK). OK organizer Jim Schell says members will meet in small groups and pick apart one another's companies. The OK program to date has been available only on a pilot basis in Bend, Oreg., but SCORE plans to roll out chapters in as many SCORE sites as possible.