805 ILCS 310/3
Corporations organized under this act may provide in their by-laws that when a shareholder is desirous of disposing of his stock, he shall first give the corporation an opportunity to purchase the same, after reasonable notice; and nothing in this act shall be construed as prohibiting or preventing the making of an agreement between the subscribers or purchasers of such shares that they and each of the subscribers to the shares of capital stock of such corporation, and subsequent purchasers of shares shall, before disposing of their shares, give to the said corporation an opportunity to purchase the same, after reasonable notice, at the amount paid for said shares to said corporation and reasonable interest thereon. All shares purchased by the corporation under the provisions of this section shall be held only for sale to new shareholders.
805 ILCS 310/3