291.30. The corporation may award, after a call for public tenders published in a newspaper circulating in its territory, a contract contemplated in the second and third paragraphs of section 291.28 that involves an expenditure of not less than $50 000.
The time prescribed for the receipt of tenders shall not be less than eight days.
Tenders shall not be called for nor shall the contracts resulting therefrom be awarded except on one or the other of the following bases:(1) for a fixed price;
(2) at unit prices.