If the articles of incorporation or by-laws of a corporation subject to this Act fail to state a price or method of determining a fixed price at which the corporation or its shareholders may purchase the shares of a deceased shareholder or a shareholder no longer qualified to own shares in the corporation, then the price for such shares shall be the book value as of the end of the month immediately preceding the death or disqualification of the shareholder. Book value shall be determined from the books and records of the corporation in accordance with the regular method of accounting used by the corporation.
805 ILCS 15/16