The cost of any improvement for which special assessments may be made as herein provided shall include the purchase money of real estate or any interest therein, when acquired by purchase, or the value thereof as found by the jury, when appropriated, the costs and expenses of the proceedings, the damages assessed in favor of any owners of adjoining lands and interest thereon, the costs and expenses of the assessment, the expense of the preliminary and other service and of printing, publishing the notices and ordinances required, including notice of assessment and serving notices on property owners, the cost of construction, interest on bonds, where bonds have been issued in anticipation of the collection of assessments, and any other necessary expenditure.