Mont. Code Ann. § 7-12-4153

If the proposed improvement consists of the purchase of an existing improvement, the city council may, after the creation of the special improvement district and after ordering the proposed improvement, enter into a contract for the purchase of the improvement, upon such terms as it considers just, without advertising for bids or proposals. However, the total purchase price of the existing improvement may not exceed the amount set forth in the notice required by 7-12-4106.